Chuong4 Cac Phuong Phap Pho 2011

HANOI UNIVERSITY OF TECHNOLOGY (HUT)

INTERNATIONAL TRAINING INSTITUTE FOR MATERIALS SCIENCE

Spectroscopic Techniques Spectroscopic Techniques f M t i l S if M t i l S ifor Materials Sciencefor Materials Science

NGUYEN ANH TUAN

HANOI-2011

NI DUNG BI GING

CHNG 1 KHI NIM CHUNGCHNG 1: KHI NIM CHUNG1.1. M u1.2. Cu to vt cht, cu trc tinh th v cu trc tinh th thc , 1.3. Phn loi vt liu v cc ph/php phn tch cu trc vt cht

CHNG 2: CC PHNG PHP HIN VI2 1 Hi i h (OM)2.1. Hin vi quang hc (OM)2.2. Hin vi in t truyn qua (TEM)2.3. Hin vi in t qut (SEM) q ( )2.4. Mt s phng php hin vi khc

CHNG 3: CC PHNG PHP NHIU X3.1. C s ca nhiu x

3.2. Nhiu x tia X (XRD)3.3. Nhiu x in t (ED)3.3. Nhiu x in t (ED)3.4. Nhiu x ntron (ND)

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CHNG 4 CC PHNG PHP PHN TCH PHCHNG 4: CC PHNG PHP PHN TCH PH

4.1. M u4 2 Cc phng php ph in t4.2. Cc phng php ph in t

1). Ph quang in t (XPS)2). Ph in t Auger (AES)

3). Ph tn hao nng lng in t (EELS)4.3. Cc phng php ph photon/ph Rntgen

1). Ph tn sc nng lng (EDSEDS)1). Ph tn sc nng lng (EDSEDS)2). Ph tn sc bc sng (WDSWDS) 3). Ph hunh quang Rngen (XRFXRF)

4.4. Cc phng php ph ion/khi ph1). Khi ph ion th cp (SIMS)2). Ph tn x ngc Rutherford (RBS)2). Ph tn x ngc Rutherford (RBS)

.

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NI DUNG BI GING

CHNG 5: CC PHNG PHP HIN VI U D QUT (SPM)5.1. Hin vi lc nguyn t (AFM)5.2. Hin vi u d qut hiu ng xuyn ngm (STM)5.3. Hin vi lc t (MFM)5.3. Hin vi lc t (MFM)5.4. Hin vi quang hc qut trng gn (SNOM)5.5. Mt s loi hin vi u d qut (SPM) c bit khc

CHNG 6: CC BI THC HNH6.1. Phn tch cu trc n tinh th bng nhiu x Lauer.6 2 Ph t h t ti h th b h h hi bt6.2. Phn tch cu trc a tinh th bng phng php nhiu x bt.6.3. Phn tch pha nh tnh, nh lng.6.4. Quan st hnh thi/cu trc b mt bng hin vi in t qut.6.5. Quan st hnh thi/cu trc b mt bng hin vi lc nguyn t.

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CHNG 4: CC PHNG PHP PHN TCH PH4.1. M U

- Cc p/p nhiu x: ch yu cung cp thng tin v "hnh thi" ca cu trc bn trong: cch thc b tr, tng quan sp xp, cch thc t chc tp hp ca cc nguyn t / phn t cu trc mng tnh i xng tnh tun hon t chc pha tinh th/ phn t cu trc mng, tnh i xng, tnh tun hon, t chc pha tinh th.

- S nhiu x xut pht t s tn x n hi ca tia X, e hay n bi cc nguyn t -i tng, thc th c s nht cu thnh nn vt cht. S giao thoa ca cc tia tn x n hi trn mng ca cc nguyn t/phn t (xp xp theo mt trt t no - mng tinh th) tun theo nh lut Bragg thng khng quan tm n nng lng ca cc tia/ht (Mt s p/p hin vi mc d s dng c s tn x khng n

C / hi i h h th i d h h d b i t

hi v hp th (do mt mt nng lng) tuy nhin cng ch bit c nhng thng tin c tnh cht bn ngoi cu trc ca nguyn t/phn t.

- Cc p/p hin vi: ch yu cho thy ci dng v, hnh dng bn ngoi ca vt: ngha l nhng ci thuc v "hnh thi" ca v bn ngoi, b mt l chnh (nh cnh quan b mt: li, lm,; hay hnh dng: trn, vung,); hoc mc vi m

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hn, l ci v bao bn ngoi ca cc nguyn t/phn t V c bn cng khng phn bit c loi nguyn t v cu trc bn trong ca nguyn t/phn t.

CHNG 4: CC PHNG PHP PHN TCH PH4.1. M U

- Ngoi nhng thng tin chung lin quan n tnh tng th", tnh "hnh thi" bn

ngoi nu trn cc tnh cht khc lin quan ti bn cht bn trong ca vt cht/vtngoi nu trn, cc tnh cht khc lin quan ti bn cht bn trong ca vt cht/vt

liu rt cn c bit: thnh phn ho hc (loi nguyn t), lin kt ho hc, bn

cht ca cc lin kt,... ngha l cn nhng phn tch c chiu su hn vo bn

trong ca vt cht, vo n tn cu trc bn trong ca cc nguyn t/phn t cu

thnh nn vt cht/vt liu.

- Phn tch ph cho bit ci bn trong, TG ca cc nguyn t: nguyn t g ? Cc trng thi lin kt ca ng.t cht g ? pha g ? v.v y quan tm n nng lng ca cc qu trnh tng tc, tn x, nhiu x.

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CHNG 4: CC PHNG PHP PHN TCH PHCu trc/cu to vt cht qua cc cp quan st: 11) Hnh thi bn ngoi Cu trc th tinh

2

1) Hnh thi bn ngoi Cu trc th , tinh mc v m.

2) Hnh thi bn trong nng: Cu trc pha tinh th cc t chc t vi - tinh mc vi m.

23) Hnh thi bn trong su: Cu trc tinh th tinh thang/mc nguyn t: TG ng.t, ph.t.

4) Cu trc ca ng. t, ph. t: TG cc ht s cp(Cu trc di ng t (subatomic) to nn cc ng t)(Cu trc di ng.t (subatomic) to nn cc ng.t)5) Cu trc ca cc ht s cp: TG cc ht c bn -

- in t v cc ht nhn nguyn t.6) . ? Cc ht quark cu to nn cc ht s cp.6) . ? Cc ht quark cu to nn cc ht s cp.

??6

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??3 4 56

CHNG 4: CC PHNG PHP PHN TCH PH- Nguyn tc chung ca phn tch ph:

K h h h/b h b CR b h ( i h h ) h+ Kch thch/bn ph b mt CR bng cc ht (-, ion, ht trung ha,) hay photon; hoc bng cc trng vt l (in trng, t trng, trng nhit,...).

+ Din ra cc qu trnh, cc tng tc ca cc ht hay bc x vi cc nguyn t trong mu, ngay trn hay gn b mt mu gy pht x/bc x th cp.

+ Pht hin v ghi cc ht hoc photon (bc x) th cp thot ra khi b mt mu(hoc cc trng thi kch thch th cp khc).( g p )

+ o/phn tch cng cc ht/photon pht x phn gii theo nng lng/bc sng hoc theo bt k mt i lng vt l c trng no bng cc k thut

khc nhaukhc nhau.

cc k thut/phng php o ph. ph: mt tp hp cc c trng

i

1

(thng l cc i lng vt l tiu biu cho vt th/vt cht/vt liu) c biu din, c trin khai, c tri ra theo mt i lng vt l tiu biu khc

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V d: Mt lng knh phn tch nh sng trng thnh cc nh sng c bc sng khc nhau (mu sc).

123....

mt i lng vt l tiu biu khc.

CHNG 4: CC PHNG PHP PHN TCH PH- Nguyn l chung ca KT phn tch ph

Ngun kch thch ph1Ghi, o, phn tch ph3

Hin th kt qu: thng tin vHin th kt qu: thng tin v cu trc nguyn t ca mu2

4

M k h

?? !!

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Mu c kch thch ph

CHNG 4: CC PHNG PHP PHN TCH PHDanh sch cc ch vit tt thng gp trong k thut phn tch ph:

AESAES - Auger electron spectroscopy APS - Appearance potential spectroscopy CAICISS - Coaxial impact collision ion scattering spectroscopy EDXEDX - Energy dispersive X-ray spectroscopy (EDSEDS); see EPMAEPMAEELSEELS - Electron energy loss spectroscopyEPMAEPMA- Electron Probe Microanalysis ESCAESCA - Electron spectroscopy for chemical analysis; see XPSXPSGDMS - Glow discharge mass spectrometry GDOS - Glow discharge optical spectroscopy HREELS High resolution electron energy loss spectroscopyHREELS - High resolution electron energy loss spectroscopy IAES - Ion induced Auger electron spectroscopy IIX - Ion induced X-ray analysis INS - Ion neutralization spectroscopy p pyIRS - Infra Red spectroscopyISS - Ion scattering spectroscopy LEIS - Low energy ion scattering LIBS Laser induced breakdown spectroscopy also: LIPS Laser

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LIBS - Laser induced breakdown spectroscopy - also: LIPS - Laser induced plasma spectroscopy

LOES - Laser optical emission spectroscopy

CHNG 4: CC PHNG PHP PHN TCH PH

LS - Light (Raman) scattering S g t ( a a ) scatte gMEIS - Medium energy ion scattering NDP - Neutron depth profiling NEXAFS - Near edge X-ray absorption fine structure PD PhotodesorptionPD - Photodesorption PDEIS - Potentiodynamic electrochemical impedance spectroscopy PIXE - Particle (or proton) induced X-ray spectroscopy RBS - Rutherford backscattering spectroscopy g p pySCANIIR - Surface composition by analysis of neutral species and ion-

impact radiation SEIRA - Surface enhanced infrared absorption spectroscopy SERS S f E h d R S tSERS - Surface Enhanced Raman Spectroscopy SEXAFS - Surface extended X-ray absorption fine structure SIMSSIMS - Secondary ion mass spectrometry SNMS - Sputtered neutral species mass spectroscopy TXRF - Total Reflection X-ray fluorescence analysis UPS UPS - UV-photoelectron spectroscopy XAES - X-ray induced Auger electron spectroscopy XPSXPS - X-ray photoelectron spectroscopy

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y p p pyXRFXRF - X-ray fluorescence analysis


4.2. Phng php phn tch ph in tph in t

1) Ph i t (XPS/ESCAXPS/ESCA)1) Ph quang in t (XPS/ESCAXPS/ESCA)

2) Ph in t Auger (AESAES)

3) Ph tn hao nng lng in t (EELSEELS)3) Ph tn hao nng lng in t (EELSEELS)

4) Cc k thut phn tch ph in t khc

4.3. Phng php phn tch ph photong p p p p p

4.4. Phng php phn tch khi ph ion

Lu : Mi p/p trnh by gm 4 phn:

- nguyn l chung- thit b chung

Thi/k.tra

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- b phn tch: cu to & nguyn l lm vic- cc vn m rng ng ch khc


- Cc k thut ph in t phn ln lin quan n cc qu trnh chuyn di in t cc mc li cch gi khc:

- Cc k thut mc li c chia

cc mc li cch gi khc: cc k thut ph mc li

lm 2 nhm k thut, tng ng vi s to ra hay hy cc l trng trong cc mc li:trng trong cc mc li:

1- To ra cc l trng trong cc mc li hnh thnh nn cc k

2- S hy cc l trong cc mc li hnh thnh nn cc k thut c bn gm:

mc li hnh thnh nn cc k thut c bn gm:

- X-ray Photoelectron Spectroscopy (XPS)

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- Auger Electron Spectroscopy (AES)- X-ray Emission Spectroscopy (XES)

p py ( )- X-ray Absorption

Spectroscopy (XAS)

CHNG 4: CC PHNG PHP PHN TCH PH1) Ph quang in t (Photoelectron Spectroscopy, PES )

Nguyn l:- Nguyn l chung l s dng photon kch thch pht x in t th cp b mt mu. - o v phn tch nng lng ca in t pht x th cp bit thng tin v tnh cht b mt.

h

Photon (tia X, UV,

l )

in t (quang in t) pht x.

K hiu l p.M L1, laser,...)

Hin tng quang ion ha

X ray

ML2,

K

+ X-ray Photoelectron Spectroscopy (XPS) s dng bc x tia X mm (h ~ 200-2000 eV) kim tra/thm d cc mc li (core-levels) (hoc cn gi l Electron Spectro-

X rayE = h p

000 e ) t a/t d cc c (co e e e s) ( oc c g ect o Spect oscopy for Chemical Analysis, ESCA).

+ Synchrotron X-ray Photoelectron Spectroscopy (SXPS): s dng bc x tia X ng b (h ~ 100-1000 eV).

+ Ultraviolet Photoelectron Spectroscopy (UPS) - s dng bc x tia cc tm (UV) c nng lng h ~ 10-100 eV kim tra/thm d cc mc ho tr.

- ng dng ch yu: phn tch thnh phn ha hc v lin kt b mt cht rn.NATuan-ITIMS-2011

CHNG 4: CC PHNG PHP PHN TCH PHng nng ca in t pht x:

E (h X) h E E h E h - Hng s Planck ( 6.62 10-34 Js ) - Tn s ca bc x quang (Hz)X - Cc mc K hoc L1 L2 L3 b kch thch

Ekin(h, X) = h - EB - S EB = h - Ekin - S

- Cng thot ca mt s kim loiX Cc mc K hoc L1, L2, L3,... b kch thch. EB - Nng lng lin kt (binding energy)S - Cng thot b mt (work function), rt nh v hu nh khng i i vi phn ln cc kim loi.

thng dng

In Air* UHV**

Fermi levelFe 4.35 [eV] 4.50 [eV]

Ni 4.25 [eV] 5.15 [eV]

Cu 4 45 [eV] 4 65 [eV]Cu 4.45 [eV] 4.65 [eV]

Al 3.60 [eV] 4.20 [eV]

Zn 3.80 [eV] -

E

Ekin

h

[ ]

Au 4.78 [eV] 5.10 [eV]

* M. Uda ; Jpn. J.Appl.Phys. 24,284 (1985)** D E E t Ph R B2 1 (1970)

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EB h ** D.E. Eastman ; Phys.Rev. B2, 1 (1970)

S ca KL khc nhau khng nhiu !

CHNG 4: CC PHNG PHP PHN TCH PHYu cu ca thit b:- Chn khng UHV: ~ 10-8 Pa (~10-10 Torr hay mBar)Chn khng UHV: 10 Pa ( 10 Torr hay mBar)- V thit b c lm bng vt liu t c t thm

cao (vt liu -metal) nhm ngn chn nh hng ca t trng (ca tri t v cc thit b khc).

Ph k quang - Ngun tia X: i hi bc x c trng c nng

lng cao, ~ > 1 keV, yu cu cao v phn gii nng lng: rng vch ca bc x c trng

q gin t (PES)

Y MEnergy: h =

132.3 eVLine width:

Zr MEnergy : h =

151.4 eVLine width:

Mg KEnergy : h =

1253.6 eVLine width:

Al KEnergy : h =


Si KEnergy : h =


tia X cn phi rt hp, < 1.0 eV.

Line-width: 0.47 eV

Line-width: 0.77 eV

Line-width: 0.70 eV

Line-width: 0.85 eV

Line-width: 1.00 eV

- Ngun bc x ng b (synchrotron radiation): + Trong mt s trng hp cn ngun c th iu bin

nng lng c: nng lng kch thch c bin thin lin tc. S dng ngun bc x ng b: gia tc in t vi vn tc (tng i tnh) ln bc x phton tia X c ph lin tc (my gia tc ht in tch).

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+ L do: thit din quang ion ha ca cc nguyn t hay nhm cc nguyn t thay i cn c bc x thch hp "thm d" (VD: cc VL a nguyn t).

CHNG 4: CC PHNG PHP PHN TCH PHNgun tia X: S pht x tia X bng va chm in t (bn ph - bc x hm)

e1Incident electron C ch pht x tia XC ch pht x tia X

K: lp v/qu o vi n = 1 (lp v trong cng)(lp v trong cng), L: vi n = 2, M: vi n = 3,N: vi n = 4,

Nng lng tng ng viX-ray

Nng lng tng ng vi mi mc n ca mt nguyn t c nguyn t s Z bng:E = - 13.56 (Z/n)2 (eV)

e2(photo-electron inelastic-

scattered electron)

e1 (elastic-scattered electron)

Khi cc electron s cp nng lng kchLu : ring /v vch K, do hiu ng mn chn (screening effect) ca electron khc mc n = 1, nn (Z-1) c thay cho Z. Tng qut hn: (Z-1) cn c thay bng (Z-), i t h hi h

Khi cc electron s cp nng lng kch thch cc electron lp v li (K) ca nguyn t, lm bt electron ca lp ny i, li mt l trng, mt electron t lp v L nhy n lp v K. C 2 kh nng c th xy ra (cnh tranh nhau): hoc l pht ra tia X c trng hoc l

( ) ( ) )(117.1021

11156.13 222

2 eVZZEEE Lk

==vi tnh n hiu ng mn chn.

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nhau): hoc l pht ra tia X c trng, hoc l tia X truyn nng lng cho in t lp v ngoi n c nng lng thot ra khi ng.t - Auger electron (khng cho thy y).

CHNG 4: CC PHNG PHP PHN TCH PHNgun tia X: S pht x tia X bng va chm in t (bn ph - bc x hm)

ng pht tia Xng pht tia X Do Coolidge (ngi c) pht minh ra vo khong nm 1912. Electron c gia tc vi nng lng cao i n anode Electron c gia tc vi nng lng cao i n anode. Electron ti tng tc vi cc nguyn t ca anode (VD: Mg,

Co, hoc Cu), gy ra bc x tia X c trng (bc x hm).

X-ray

ng pht tia X kiu ngun im

Hot filament emits electrons

e ngun im

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Ngun tia X: S pht x tia X bng va chm in t (bn ph - bc x hm) CHNG 4: CC PHNG PHP PHN TCH PH

ng pht tia Xng pht tia X

-50 kV

H OH2O vo/ra

Anode quay vi vn tc 6000 rpm

ng pht tia X kiu anode quay(C cng sut pht cao hn)

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Ngun sng cao cp: Pht x tia X/nh sng bng bc x ng b (gia tc)


Storage Ring

Shield Wall

Bc x ng b (Synchrotron radiation - SR): Bc x in t (light) c pht x t cc in t chuyn ng vi vn tc tng i tnh Do in

t i t h i t h i t h t c gia tc, v chuyn ng vi vn tc so snh c vi vn tc nh sng. Ln u tin, vo nm 1947, c quan st thy t my gia tc in t (electron accelerator) 70 MeV c. Sau SR ch c coi nh mt th "cht thi", lm hn ch cht lng ca my gia tc.

Nhng sau ngi ta nhn thy SR l ngun sng ny, gm cc loi hng ngoi (infrared), tia cc

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g g y g g y g g g ( ) tm (ultraviolet), v tia x, rt hu ch cho cc nghin cu vt cht thang nguyn t, phn t., v ngy nay cng thng c s dng cho cng ngh quang khc bng tia X (x-ray lithography).

Bc x c tnh phn cc cao v dng xung tn s cao (v d, xung nano giy).

Nguyn l bc x dao ng sng do hin tng dch Doppler v pha sng nmNgun sng cao cp: Pht x tia X/nh sng bng bc x ng b (gia tc)


Nguyn l bc x dao ng sng do hin tng dch Doppler v pha sng nm

Bc x ng b t cc in tr chuyn ng gia tc tng i tnh (relativistic electrons)- Khi cc ht in tch, VD e, chuyn ng trong mt t trng c to ra bi cc vin nam chm b tr tun hon, cc e s nhn thy mt cu trc nam chm tun hon chuyn ng thng v pha chng vi mt chu k b thu nh li mt cch tng i: = u/ (u l chu k ca nam chm, 1/(1- 2)1/2, v/c)- Tn s ca bc x c pht x ra bng f = c/=c/u.

f f/ / - Khi ti ngi quan st, dng tng i tnh ca cng thc tn s Doppler l: f = f/((1-)) = c/(u(1 - )) 22c/u. (khi 1 1 - 1/22). V vy tn s c quan st thy l: = c/f = u /22.VD: khi e c nng lng 1.9 GeV, = 1900/0.511 = 3718; vi u = 5 cm, cho ra = 1.8 nm (tng ng vi tia X).

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Nguyn l to bc x ng b do s un ln (Wiggler) hoc dp dn (undulator)


i vi s bc x bng nam chm un cong chm tia, cc in t c gia tc, hay c un, bng t trng ng u uniform magnetic field (B dc theo chiu +z, qu o ca in t cong theo hnh trn).

Bng cch t mt dy cc nam chm vnh cu, t trng ln lt ln (phng +z) v xung (phng z), gy ra cho ht in tch b b cong ti lui, dc theo mt phng ngang.

mi ch b b cong qu o, cc in t pht ra bc x ng b trong vng ph tia X.

Qu o ca ht

(positiveelectron)

ca t

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S pht x bc x ng b din ra nh th no ?Nam chm un cong: Vi cm ng t thng


Ngun ht (in t) Nam chm un cong: Vi cm ng t thng thng c s dng l B 1.5 Tesla. Dng ch C cho php bc x i ra.

Ngun ht (in t) c phng t y

ng thng

Ch un Ch un v pht ra khi qua mt nam chmc

r

Mt my gia tc phng cc chm ht in t vo vng gia tc (storage ring) theo ch xung

gia tc ti y

3)GeV()m(559.0)nm(

Er

c = Mt my gia tc phng cc chm ht in t vo vng gia tc (storage ring) theo ch xung

pico giy (pico-second pulses) vi cc dng xung ca ht in tch cch nhau tng t khong mt vi phn ca nano giy.

S gia tc c to ra bng mt in trng xoay chiu c tn s radio (RF radio frequency) sao cho ng b vi tn s qu o (orbital frequency).

Mt min lin tc ca bc x c pht ra bi mi chm ht khi n c thay i hng gia tc (ti mi v tr t nam chm in) vi bc sng trung bnh (hay ti hn) l c ~ r / E.

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S phn b gc ca bc x ng bCHNG 4: CC PHNG PHP PHN TCH PH

Khng c bc x dc theo hng gia tc. Bc x mnh nht hng vung gc.

P: cng sut pht x

g p a: gia tc: gc khi

Gc m hnh cone1/~ 1/

Trng hp II: Trng hp II: vv//c ~ 1c ~ 1

vv//c 1c 1Trng hp I: Trng hp I:

vv//c

Ph ca bc x ng b (nam chm un cong)CHNG 4: CC PHNG PHP PHN TCH PH

Bending MagnetBending Magnet

(critical energy)

1.24nmPh tia X pht x ng b l ph lin tc

Nng lng ngh ca in t = mc2 = (9.110-31)(3108)2 = 8.1910-14 J = 0.511 MeV (rt nh).Nng lng tng cng ca in t = mc2, with = 1/(1-v2/c2)1/2.Vi nng lng l 1.0 GeV, = 1000/0.511=1957, v vy v/c = 0.99999987, ngha l v rt gn vi c.

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Chn lc bc sng bng s dng b lc sc (monochromator) bi nhiu x tia X


T ph lin tc ca tia X pht x ng b pht ra, vic tch ra/chn lc ph n sc bng phng php

n = 1, 2, 3lc ph n sc bng phng php nhiu x tia X trn n tinh th.

d : khang cch gia cc mt phng mng tinh th

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CHNG 4: CC PHNG PHP PHN TCH PHPh k quan in t Ph k quan in t -- PESPES

Nguyn l chung ca ph k PES

EB = 0 at EF

Ekin

o Ekin = h - EB - S

Xc nh c EB = (h - S ) - Ekin(c trng cho cc nguyn t ha hc)

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Xc nh c nguyn t ha hc & lin kt


V d: mt ph XPS ca Au pAu-4f

Au-5d

A 5dAu-5d

- C th thy r cc trng thi nng lng in t mc li (4f) v dng di ho tr cn kh th ca Au (5d).

- Mc d c th thy di ho tr bng XPS, nhng phn gii nng lng vn cha cao nn

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cn hn ch trong vic nghin cu chi tit gii ho tr. - Tuy nhin ph XPS nhy vi mi trng ho hc, nn c dng phn tch trng thi ho

hc ca mu.

CHNG 4: CC PHNG PHP PHN TCH PH- B phn tch nng lng p ca ph k PES: (k hiu p ngha l .t pht x do tng tc

i ht i t)vi phton - quan in t)+ B phn tch bn cu ng tm (Concentric Hemispherical Analyzer, CHA) c s dng

ph bin cho cc k thut phn tch ph in t ni chung.+ c trng tiu biu ca b phn tch CHA l kh nng phn gii nng lng+ c trng tiu biu ca b phn tch CHA l kh nng phn gii nng lng.

* phn gii tuyt i: E FWHM ca mt peak c chn, khng ph thuc vo v tr ca peak.

* phn gii tng i: R = E/E (E l ng nng ca v tr nng lng peak) ph thuc vo v tr ca peak R c quy v cho mt ng nng ca p c th.

* Cc th m -V2 v -V1 vi V2> V1, c tc dng un cong qu o ca p.* N S ti i F t O l h* Ngun S, tiu im F v tm O l ng phng.* Mt bn cu ng vi r0 l ng th gia 2 cc bn cu r2 v r1.

S cu to ca b phn tch bn cu ng tm CHA

- Khi cc p c nng lng eV0 c pht ra t S v i dc theo mt ng th (c th tng ng l V ) chng s hi t

-V2

r0

r2

r1

theo mt ng th (c th tng ng l V0), chng s hi t F nu: V2 - V1 = V0(r2/r1 - r1/r2)

- Nu cc p c phng ra khng chnh xc dc theo mt ng th m b phn tn theo mt gc no xung

NATuan-ITIMS-2011

-V1 rng li vo wS

rng li ra wF

S F1

O

ng th, m b phn tn theo mt gc no xung quanh hng chnh xc ca mt ng th chng s hi t F nu: E/E = (wS + wF)/4r0 + ()2

CHNG 4: CC PHNG PHP PHN TCH PH- Trong phn ln cc thit b s dng cho mc ch phn tch thng thng, wS = wF = w

E/E = w/2r0 + ()2

(w v r0 l hng s)

D c iu khin bng cc in p V1 v V2ca hai in cc bn cu ng tm ca b CHA

chn lc cc in t c nng lng tng ng.

B phn tch CHA

Detectorsin tThu knh 2Chm

- Cu trc ca cc ph k XPS hin i ngy

nay c b phn quang in t hi t cc in tChm tia p

Thu knh 1

nay c b phn quang in t hi t cc

in t vo ca s S v detector ca s F

c th gm mt s b phn tch in t n

knh hay tm phn tch a knh

NATuan-ITIMS-2011

MuNgun tia X

knh hay tm phn tch a knh.

CHNG 4: CC PHNG PHP PHN TCH PHThng tin t ph XPS:+ c trng chnh, hay c trng ban u/nguyn thy: dng ph rng thng tin v nguyn t

ha hc v cc mc lin kt tng ng.+ c trng ph, hay c trng chi tit: dng ph hp thng tin v cc lin kt tinh t (nh

li kt i )

4d5/24d3/2

Ph XPS qut di nng lng rng: 0 - 1100 eV

lin kt spin qu o).

C t h h ionizationpotential

4p3/24p1/24s

3d

Cc nguyn t ha hc v cc mc lin kt tng ng

3d5/23d3/23p3/23p1/23s3s

2p3/22p1/22s

NATuan-ITIMS-2011

1sj: Total angular momentum: j = l + s l = 0, 1, 2, 3, ...; s = j = 1/2; 3/2; 5/2, ....


VD o ph XPS ca Pd: i vi ph XPS rng

o ph ng nng ca in t pht x:

Ekin(h, X) = h - EB - S

Tnh ton c ph nng lng lin kt:

EB = (h - S ) - Ekin

(1) (5)

valence band (4d,5s)

(3)(4)(2)

- Ph XPS thc thu c t mt mu kim loi Pd s dng bc x Mg-K

- Ph XPS tng ng biu din theo nng lng lin kt (BE). Cc mc 3p v 3s ng vi cckim loi Pd s dng bc x Mg K.

- Cc peaks chnh (ng nng ca in t tng ng) xut hin cc nng lng (KE) 330 (1), 690 (2), 720 (3),

lin kt (BE). Cc mc 3p v 3s ng vi cc peak 534/561 eV v 673 eV.

- Mc 3d ng vi peak 335 eV.- Cc mc 4p v 4s ng vi cc peak rt yu 54

v 88 eV.

NATuan-ITIMS-2011

910 (4) v 920 eV (5).v 88 eV.

- S pht x ha tr (4d,5s) xut hin mt nng lng lin kt nm trong khong 0 - 8 eV (c o ti mc Fermi).


VD v gin ph XPS hp ca Pd: chn lc mc nng lng lin kt ca 3d

valence band (4d,5s)

S pht x quang 3d trong thc t b tch thnh 2 peaks, mt 334.9 eV BE v mt 340.2 eV BE vi t s cng khong 3:2 Hin tng ny xy ra do hiu ng lin kt spin queV BE, vi t s cng khong 3:2. Hin tng ny xy ra do hiu ng lin kt spin-qu o (spin-orbit coupling) trong trng thi cui cng To ra mmen goc tng cng (totalangular momentum) l: j = l + s = 3/2 v 5/2.

NATuan-ITIMS-2011

CHNG 4: CC PHNG PHP PHN TCH PHUltraviolet Photoelectron Spectroscopy (UPS)

Ph quang in t s dng ngun tia cc tm (UV)

UPS l mt trong nhng cng c hu ch nht trong vic nghin cuhu ch nht trong vic nghin cu cc cu trc di ho tr ca cc cht ngng t (cht rn). Thng cc vch bc x ca He I (hv = 21.22 eV) hoc He II (hv = 40.8 eV) c

dng lm ngun photon kch thch. So vi XPS, phn gii ca UPS cao hn (~ meV), v th n thch hp hn trong vic nghin cu cu trc di so vi XPS

S ca ng m h (Open counter) v dng sng cc li ng bng (quenching grid) li nn

(Yield [cps])1/2

trc di so vi XPS.

(quenching grid), li nn (suppresser grid) v tin K cng sut.

NATuan-ITIMS-2011Nng lng photon ti [eV]

CHNG 4: CC PHNG PHP PHN TCH PH Trong k thut UPS, ngun bc x thng s dng l n phng in kh him, nh n

phng in kh He pht ra bc x He I c nng lng 21 2 eVphng in kh He pht ra bc x He I c nng lng 21.2 eV. Bc x ny ch c th ion ho cc in t t cc mc ngoi cng ca nguyn t, nghi l

cc mc ho tr. u im chnh ca vic s dng bc x UV so vi tia X ch, c rng vch bc x rt

h th l ht ( th ) t hthp v c thng lng phton (quang thng) cao t n pht. Nhng ng dng chnh i vi phng php UPS:

Xc nh cu trc in t ca cht rn: do c th kho st vi phn gii tt theo gc nn cho php xy dng c ton b s cu trc di trong khng gian-k. p p y g g g g

Nghin cu s hp th cc phn t c cu trc tng i n gin trn b mt kim loi: bng cch so snh cc orbitals phn t ca cc cht hp th vi c phn t c lp v kt hp vi tnh ton.

VD (hnh bn): ph UPS thu c t b mt (110) ca Cu. Tdng ph ny, sau khi tch nn ph th cp (phn gch cho ln) do phng tn x n hi, c th thu

NATuan-ITIMS-2011

c bn sao ca mt trng thi in t (DOS) ca mu. Vi v d y, c ththy cc di 3d, 4s v mc Fermi.

CHNG 4: CC PHNG PHP PHN TCH PH2) Ph in t Auger (AES)

A~2 - 10 keV

Nguyn l:

- Kch thch b mt mu bng cc in t c nng lng ~ 2 -10 keV Qu trnh pht x Auger-.

~2 - 10 keV

p g- Tt c cc nguyn t c Z 3 (Li) u c th pht x Auger-.- Ghi v o phn b nng lng ca cc Auger- pht ra t mu.- Phn tch cc Auger- theo nng lng. Xc nh c

in t (Auger-) pht x. K hiu l A.

nguyn t ho hc & trng thi ha hc.

Qu trnh pht x Auger-:- Kch thch nguyn t bng bn ph c nng g y g p g

lng ln (1-10 keV):(1) Ion ha lp v bn trong: pht ra li

mt ch trng.(2) Ch trng c lp y bng mt lp(2) Ch trng c lp y bng mt lp

v bn ngoi.(3) Qu trnh lp ch trng (2) lm gii phng

nng lng bc x tia X c trng (4a).

NATuan-ITIMS-2011

(4b) Nu tia X tng tc vi in t th ba,lm cho in t ny nhn nng lng b bt ra A

e th cp pht x - li l trng.

e th cp pht x - li l trng.

CHNG 4: CC PHNG PHP PHN TCH PHQu trnh pht x Auger-:

- Nh thy, nng lng ca c tia X bc x v Auger- u c xc nh bng cc mc nng lng ca nguyn t,

th h t h t h / 2 c th phn tch tng hp /v c 2 qu trnh ny.

- S pht x photon tia X (hunh quang tia X) v pht x l cc qu trnh cnhX) v pht x A l cc qu trnh cnh tranh nhau. Nhng /v cc lp v khng su th qu trnh Auger vn c nhiu kh nng hn.

Ekin (KL1L23) = EK - EL1 - EL23 - Einter(L1L23)E

- ng nng ca A c xc nh bi:

- ER - SEK: nng lng ca li K; EL: nng lng

tng ng /v cc lp v ngoi L.Einter: nng lng tng tc gia cc l

NATuan-ITIMS-2011

trng trong lp v L1 v L23.ER: tng cng cc nng lng hi phc nguyn t.

CHNG 4: CC PHNG PHP PHN TCH PHYu cu v thit b

8 10- Chn khng UHV: ~ 10-8 Pa (~10-10 Torr hay mBar)- V thit b c lm bng vt liu t c t thm cao (vt liu -metal) nhm ngn chn nh hng ca t trng (ca tri t v cc thit b khc)t trng (ca tri t v cc thit b khc).

B phn tch gng tr (CMA)

NATuan-ITIMS-2011

Ph k AES model PHI660. S ca b vi u d Auger dng trong h PHI660.

g g ( )


Auger Electron Spectroscopy,Low Energy Electron Diffraction

NATuan-ITIMS-2011

CHNG 4: CC PHNG PHP PHN TCH PH- Ngun :

=

Cost Lifetime

W= $15 100 hr. L B6 $400 1000 h

Khng ging nh trong XPS nng lng photon (h) c tnh n trong phng

LaB6 = $400 1000 hr F.E. = $6000 5-8,000 hr.

trnh nng lng, trong khi , AES nng lng ca dng kch thch khng c mt trong phng trnh nng lng. V vy thot nhn cho thy tnh cht phn tn nng lng s khng thch hp cho k thut AES. Thc t cc s cp vn thch hp v thit din cho vic ion ha do va chm ph thuc vo nng lngva chm ph thuc vo nng lng.

NATuan-ITIMS-2011


Quang in t ca b sng e:Qua g t ca b s g e

2

5

-

5

0

k

V

~

2

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~ 1 m ~ x 10 nm

CHNG 4: CC PHNG PHP PHN TCH PH- B phn tch nng lng ca A: C s dng c

b h t h CHA ?+ K thut phn tch AES s dng b phn tch gng hnh trCMA (Cylindrical Mirror Analyzer).

- V

b phn tch CHA ?

e-gunF

r1r2

42.30

Fw

L

Quan h gia nng lng E v th V:E = 1.31 eV/ln(r2/r1)

NATuan-ITIMS-2011

Nu gc phn tn trong mt khong , in hnh ~ 6o, phn gii nng lng tng i ca mt CMA l:

E/E = 0.18 w/r1 + 1.39()3Models BDL800IR-MCP


Cc h s dng b phn tch CHA kt

hp phn tch a nng ph in t

(XPS & AES)

NanoSAM Lab Auger Electron Analyser

(XPS & AES)

MICROLAB 350 - Auger Electron Spectrometer

Thit b phn tch ph in t a nng AXIS 165: X-ray Photoelectron Spectroscope (ESCA, XPS)/ Auger Electron Spectroscope (AES)

Sng in t

NATuan-ITIMS-2011

Ch : thng c sng ion bc lp b mt mu.

Sng ion

CHNG 4: CC PHNG PHP PHN TCH PHH phn tch ha hc b mt (chemical

surface characterization) Escalab 250Xi csurface characterization) Escalab 250Xi c th phn tch a chc nng:

XPS, UPS, AES, SAM, REELS(SAM = Scanning Auger Microscopy; REELS = Reflected Electron Energy Loss Spectroscopy)

NATuan-ITIMS-2011

CHNG 4: CC PHNG PHP PHN TCH PH- Ph nng lng ca A: + Thng thng ph AES c trnh by di dng phn b nng lng vi phn dN(E)/dE+ Thng thng ph AES c trnh by di dng phn b nng lng vi phn dN(E)/dE,

trong khi ph XPS li s dng dng phn b nng lng tch phn N(E). Cch s dng ny lm tng cng kh nng pht hin cc c trng Auger.

- Ph AES ca Cu di dng mode tch phn (integral mode spectra)phn (integral mode spectra).

(after Goldstein et al. 1981)

Cc mode ph tch phn v vi phn v d ca Cu vi

- Ph AES ca Cu tng ng di dng mode vi phn (differential mode spectra)

NATuan-ITIMS-2011

Cc mode ph tch phn v vi phn, v d ca Cu vi cc peaks mnh nht: A M2,3M4,5M4,5; B

L3M4,5M4,5; C L3M2,3M4,5; D L3M2,3M2,3.


Ph t h th h h h t h AES h t (ti bi 1% l b t) i iThng tin t ph AES:- Phn tch thnh phn nh tnh: AES c nhy rt cao (tiu biu ~ 1% n lp b mt) i vi

tt c cc nguyn t, ngoi tr i vi H v He. Mi nguyn t trong mu s cho nhng b vch ph Auger l cc peak c nhng ng nng khc nhau tng ng c trngvi nguyn t .

- Phn tch thnh phn nh lng (s dng mu chun).- Ngoi ra: phn tch theo ch phn b nng lng Auger theo su - Auger Depth Profiling, v ch hin vi in t Auger (cn gi l Auger mapping) - Scanning Auger Microscopy (SAM).

VD v phn tch AES ti mt im

2

4

0

2

7

5

3

3

0

2

4

0

2

7

5

3

3

0

NATuan-ITIMS-2011

Ph Auger o thc (biu din di dng phn b tch phn nng lng, N(E)) ca Pd kim loi thu c khi s dng chm tia 2.5 keV to ra qu trnh chuyn di Auger. Cc peak chnh xut hin gia khong 220 & 340 eV.

Ph Auger ca Pd biu din di dng vi phn, dN(E)/dE.

CHNG 4: CC PHNG PHP PHN TCH PH VD v phn tch AES ti nhiu imKi d d h ki C A b Si/SiOKim tra mt dy dn hp kim Cu-Ag nm trn b mt Si/SiO2

Ph AES cho thy xut hin cc peak Auger (c nh du) v t l v cng ca cc peak . Nn ca cc ph ny khng nh nhau, ty thuc vo sng khc nhau ca vng

NATuan-ITIMS-2011

peak . Nn ca cc ph ny khng nh nhau, ty thuc vo sng khc nhau ca vng c kho st nh in t th cp (SEI) (nh3). Nguyn nhn l do s phn x mnh

nhng vng c cha cc nguyn t nng (nguyn t s Z ln ng vi min sng hn), nh Ta (#2) v gim cc nguyn t nh hn nh Ag (#3), Cu (#1) v ti SiO2 (#4) c ti nht.


VD v phn tch AES phn b theo chiu su ca mu

Phn tch s phn b cc nguyn t ha hc theo chiu su trn b mt cht rn bng in t Auger (Auger Depth Profiling - ADPADP)

p p

Chm tia in t s cp

B mt ban u ca mu

in t Auger

Sng ionin t Auger

Sng ionin t Auger

Sng ionin t Auger

NATuan-ITIMS-2011

Sng ionin t Auger

CHNG 4: CC PHNG PHP PHN TCH PHScanning Auger Microscopy (SAM) Xy dng bn phn b cc nguyn t

bng vi u d Augerbng vi u d Auger

Cc im c phn tch (mu )

Phn tch AES theo cc ng ngang (mu ) qut t trn xung

Ph AES tng ngthu c

NATuan-ITIMS-2011

nh ph AES cho thy s phn b ca cc nguyn t Ni, Fe v P.

CHNG 4: CC PHNG PHP PHN TCH PH3) Ph tn hao nng lng in t (EELS)

Nguyn l:- Trong TEM, cc nng lng cao (HEE) truyn qua mu mng tn x khng n hi

ngha l c tn hao nng lng.

tn x n hi

20 - 100 keV elastic inner-shell inelastic outer-shell inelasticEo

Eo Eo Eo Eo

in t tn x tuyn qua b tn hao nng q glng. K hiu l EL.

EL

Bc tranh tn x ht

EoE1 < Eo

E < E

Ngoi nng lng b mt, cn phi tnh n gc tn x EELS ch quan tm ti

Nh vy EELS l k thut da trn phn tch s mt mt nng lng ca chnh cc s cp b tn x do tng o nng lng tn hao ca

Bc tranh tn x ht E1 < Eo nng lng v phn b (gc lch) ca in t s cp sau khi qua mu.

g g p gtc vi mu. Thu c thng tin v bn cht cc kch thch c bn ca tinh th vng gn b mt.

NATuan-ITIMS-2011

tn x trong mt khong

gc ring EELS.

CHNG 4: CC PHNG PHP PHN TCH PHBIU DIN QU TRNH TN X KHNG N HI TRONG KHNG GIAN THC

TN X KHNG N HI BI MT IN T T DO TNH Quan h gia gc tn x v nng lng b mt

p0 incidentelectron

p0 = xung lng ca e ti.

p = xung lng ca e sau khi b tn x.free pe = xung lng ca e t do tnh nhn c

t in t ti to ra ng nng:E = pe2/(2m)

freeelectron

T tam gic mmen xung lng:pe = p0sin p0scattered

p0p

Trong c ch tn x khng n hi: ~ pe/p0 (2mE)1/2/(2mE0)1/2 = (E/E0)1/2

(E/E )1/2

pe

scattered electron

NATuan-ITIMS-2011

(E/E0)1/2

gc Bethe c nh r0 r

scatteringangle

CHNG 4: CC PHNG PHP PHN TCH PHTN X KHNG N HI BI MT IN T C LIN KT

T tam gic mmen xung lng:

p = xung lng sau khi tn x, c cho bi:2 2 + 2

p0 incidentelectron p2 = px2 + pz2

Nu px 0, p pz = p0 - dp

electron

pe = p0p pz p0 p

Nng lng khng tng i tnh: E0= p02/(2m)

dp = - p0 (dE0/2E0) = p0 (E/2E0) = p0E

boundelectron

(t E = E/2E0)

Ni chung, cho rng px ~ dp gc tn x tiu biu l:

pz p

scatteredp0 gc tn x tiu biu l: ~ px/pz ~ (p0 E)/p0 = E

D C s phn b (Lorentzian) no ca ccpxdp

scatteredelectron

NATuan-ITIMS-2011

D C s phn b (Lorentzian) no ca cc gc tn x (Tha s Lorentz biu din s phn b gc tn x ca cng tia b tn x).

scatteringangle

CHNG 4: CC PHNG PHP PHN TCH PHTha s tn x nguyn t ca in t c dng nh sau:

[ ])2/()2/(sin

12

)( 222

xe fZmvef =

=

sin

)(sin1

2sin

22

2

xe fZmvef

NATuan-ITIMS-2011


0 0Tia e tn x BIU DIN QU TRNH TN X KHNG N HI TRONG KG O

Hnh hc tn x ca thc nghim EELS bi tinh th mng- Mu tinh th rt mng (hay ch mt

s lp nguyn t b mt CR - c coi l mng 2D) Nt mng nghch

0,0

e

q

khng n hi, ks.

coi l mng 2D) Nt mng nghch c dng thanh ko di theo chiu mng ca mu Cu Ewald cho thy hnh hc tn x n hi ca cc

q//Cc "nt" mng nghchdng thanh

i s

thy hnh hc tn x n hi ca cc e b mt (hay mng mng 2D) vi cc tia tn x tho nm iu kin nhiu x Bragg. Cu Ewald

ki//ks//

- Tuy nhin, xung quang mi tia Bragg, trong mt khong gc cn c m , s c nhng tia tng ng vi cc e

Tia nhiu x, etn x n hi.

g

thc hin s tn x khng n hi, tng ng vi vect q.

- Theo /l bo ton nng lng v bo ton vect sng k:

g : vect mng nghch b mt 2D.q// : vect xung lng c truyn bi e ti, tng

ng vi vect sng ki//.

NATuan-ITIMS-2011

ton vect sng k:Es = Ei - Eks// = ki// + g + q//

g g i//ks//: xung lng tng ng vi tn hao nng

lng E ca e tn x.

CHNG 4: CC PHNG PHP PHN TCH PHC 3 nguyn nhn dn n s tn hao nng lng ca :

- S kch thch ca cc dao ng mng ca cc nguyn t b mt (cc phonon quang v m) v/hoc cc m nguyn t, phn t b hp th b mt.

- Cc kch thch ca cc chuyn di lin quan n vng ha tr (cc kch thch in t gia cc di v trong bn thn di cc trng thi b mt v trong khi cc plasmon b mt v ccdi v trong bn thn di, cc trng thi b mt v trong khi, cc plasmon b mt v cc mt phn cch).

- Cc kch thch mc li (t c th phn tch thnh phn ha hc tong t nh k thut XPS, hoc c th phn tch cu trc thng qua cu trc tn hao nng lng tinh t (phn tch ph p g q g g (p php)).

Cc kch thch trn y bao trm mt khong ph rng t vi chc meV ca tn hao nng lng /v phonon, hay cc dao ng hp th ln n vi trm eV ion ha cc mc li.

u im chnh ca k thut s dng ph EELS:

C th ti t t thi l ( li) t - Cung cp thng tin v mt ca c cc trng thi c lp y (cc mc li) v cn trng (cc mc ho tr) trong b mt cht rn.- D dng thay i c nng lng ca ti to ra mt khong nng lng rng vi cng

mt thit b m khng cn cc b lc n sc

NATuan-ITIMS-2011

mt thit b m khng cn cc b lc n sc.- thm nng ca vo mi trng lm ni bt s tn hao nng lng ca , do EELS

nhy vi trng thi b mt hn so vi cc ph quang hc.

CHNG 4: CC PHNG PHP PHN TCH PHC ch ca qu trnh tng tc dn n EELS

Ein t Auger

Xt tng tc gia e nng lng cao vi vt cht trong TEM

Qu trnh tng tc gia e nng lng cao vi cc e trong nguyn t n l

in t t doPrimary eBackscattered e

Auger e X-rays

EEvac

EDi dn

in t b kch thch vo mt trng thi kh b hi i

gHunh quang cathode

in t s cp

Secondary eCathodo-luminescence

Thin crystalline specimen

EFDi

ha tr

khng b chim gi

p

Diffracted beamDiffracted beamDirect beam

L3L2L1

Tia X c trng

E0

Hole

in t tn hao nng lng

Elastically and Inelastically Scattered eK

Tia X c trng

E- o v phn tch nng lng tn hao & s phn b gc ca cc tia tn x truyn qua khng n

Hole

NATuan-ITIMS-2011

in t tn hao nng lng

= E0 - Eb gc ca cc tia tn x truyn qua khng n hi bit c thnh phn cc nguyn t ha hc & trt t sp xp ngang trn b mt.


Qu trnh tng tc gia e nng lng cao vi cc e trong nguyn t lin kt vi nhau (cht rn)

Vacuum level

Valence or conduction band

NATuan-ITIMS-2011

CHNG 4: CC PHNG PHP PHN TCH PH ELMISKOP IA with serial EELS

http://tem.atp.tuwien.ac.at/EELS/elmi3.html

NATuan-ITIMS-2011

CHNG 4: CC PHNG PHP PHN TCH PHYu cu v thit b

- Trang b cn thit cho phn x EELS thng c kt hp vi ph k AES (thao tc ca hai loi ph k ny tng t nhau).

- B phn ph k EELS thng c cy vo cc thit b TEM v STEM vi cc b phn ch yu, gm: + B lc trong ct (in-column filter)

gm b phn tch nng lng l thu knh t; khe chn lc n.lng.

+ B lc hnh nh Gatan (gng e)+ B lc hnh nh Gatan (gng e).+ Ghi/hin th (CCD detector).

f

i

l

t

e

r

i

n

-

c

o

l

u

m

n

f

NATuan-ITIMS-2011

Gatan imaging filter(post-column filter)


- B lc thu knh t kiu cong l b phn tch nng lng ph bin, va c th hi t, va c th phn tn ("tn sc") c mt chm tia e.

R

TVTV--rate rate cameracamera

S dng CCD camera ghi ng thi

NATuan-ITIMS-2011

evB = F = mv2/RR = (m/e)(v/B)

S dng CCD camera ghi ng thi (song song) ton b di ph ph k EELS ghi song song: PEELS. Ghi hiu qu hn loi ghi tun t (SEELS)

CHNG 4: CC PHNG PHP PHN TCH PH- B lc thu knh t kiu :

Gm 4 thu knh t hnh qut to ra

t trng dng d qut b cong qu o

in t tng t nh thu knh trn trong

quang hc. tng kh nng phn ly

chm tia e theo nng lng (bc sng)chm tia e theo nng lng (bc sng)

tng "tn sc" d dng chn lc tia e c nng lng thch hp.

tch ph bin trong khong mt vi

m/eV i vi nng lng chm e s cp

khong 80 - 100 ekV

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energy-selecting slit


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CHNG 4: CC PHNG PHP PHN TCH PH Nguyn l ca lc Omega

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tn sc ~ 1.3 m/eV 200 kV. Hin nay ang k vng xung < 1 /eV hng nghn kV.

CHNG 4: CC PHNG PHP PHN TCH PHThng tin t ph EELS:

a)- Thng tin ph nh tnh- Ph EELS biu din quan h gia cng

ca cc e tn x khng n hi nh l hm ca nng lng tn hao mt gc o no ca ph k m xc nh bi m (aperture) pha trc b phn tch.

- Ph EELS c chia lm 2 vng:+ Vng tn hao thp: 0 - ~ 50 eV+ Vng nng lng cao: ~ 50 - ~ 2000 eV

(Z l k)g g g

(gii hn trn c xc nh bi cng tn hiu, m cng ny gim theo hm exp khi nng lng tn hao tng. Gii hn ny c

(Zero-loss peak)

g g g yth > 2 keV khi s dng PEELS).

- c trng tn hao cung cp thng tin v thnh phn cu to nguyn t ha hc,thnh phn cu to nguyn t ha hc,

xut hin t s ion ha cc lp v bn trong nguyn t.

NATuan-ITIMS-2011

CHNG 4: CC PHNG PHP PHN TCH PHLu : + Cc c trng trn y khng phi l cc peaks m l cc bin (g/khc) (edges) ccc peaks, m l cc bin (g/khc) (edges) c chng ln trn mt nn ph do nhng kch thch tn hao thp (nh plasmons, cc kch thch e ha tr n) hay l on cui ca mt bin ion ha ctr n), hay l on cui ca mt bin ion ha c nng lng thp hn to nn.

+ Cc bin xut hin l do cc e lp v bn trong khng ch c truyn nng lng ngng,trong khng ch c truyn nng lng ngng, m cn c truyn thm c mt cht ng nng.

x 100

O K

Ni LNi M

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Nng lng-thit din vi phn i vi s ion ha li K ca cc nguyn t nhK ca cc nguyn t nhc tnh t Hartree-Slater(Leapman et al., 1982)

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- vng tn hao zero(Zero-loss region)

- vng ion ha(Ionization region)

- vng plasmon/kch thch e-n(Plasmon/single e(Plasmon/single-e region)

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b)- Cc kch thch tn hao thp

- Trong vng tn hao thp, c trng ni bt l peak tn hao zero (zero-loss) m bn thn n

khng c ch khai thc thng tin v tn hao nng lng - l peak n hi, v ng gp ch

yu l ca cc e tn x n hi v c truyn qua mu m khng tng tc.

- Tuy nhin FWHM ca peak tn hao zero c dng nh mt php o nh gi v phn

gii nng lng ca mt ph k EEL.g g g ca p

- Trong vng ~ 5 - 50 eV, l vng ca cc peak c dng Gaussian, c ngun gc khc nhau:

+ i vi kim loi (e t do), cc peak ny l do cc dao ng tp th, ngha l plasmon ca

d t KLcc e dn trong KL.

+ Vi cc vt liu khng nhiu e t do, c mt c ch khc thay th: l s truyn nng

lng cho cc e ha tr n l. Hin tng kch thch e-n l quan trng i vi cc cht bn dn v cch in (Ghi ch: thng nhng cht ny cng pht ra cc kch thch

plasmon vng ~ 20 -30 eV).

+ Cc chuyn di gia cc di (interband transition).y g ( )

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CHNG 4: CC PHNG PHP PHN TCH PH S kch ng plasmon

- S tn x khng n hi trong CR l mt hiu ng tp th, bao gm nhiu e ca ng.t.

- Trng tnh in ca e chuyn ng nhanh gy nn s dao ng cho trng th a phng v lm thay i mt ca cc e dn (hay e ha tr).

- Cc dao ng plasmon khng ch gy a trong khi m c trn b mt. Phn dao ng plasmon b mt cng tng ln khi chiu dy muplasmon b mt cng tng ln khi chiu dy mu cng mng i, v nng lng kch thch cc dao ng ny bng 1/2 nng lng ca plason khi tng ng.khi tng ng.

- Phn tch nng lng plasmon, Epl, cho php thm d mt e a phng t do Ne, v:

NATuan-ITIMS-2011

Epl (Ne)Echenique, Ritchie & Brandt, 1979

CHNG 4: CC PHNG PHP PHN TCH PH- Nng lng Plasmon ca cc nguyn t

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+ Cc im chm trn: Ep = (h/2)(ne2/0m) vi m = m0 v n = mt e lp v ngoi.+ Cc im ch thp: Cc gi tr thc nghim (Colliex, 1984).

CHNG 4: CC PHNG PHP PHN TCH PH- S tn x khng n hi nhiu ln trong qu trnh tng tc ca e vi CR c th tng ln theo

chi d t ca m g ra s tn hao nhi ln g nhi ln kch thch dao ngchiu dy t ca mu gy ra s tn hao nhiu ln gy nhiu ln kch thch dao ng plasmon S dng s ph thuc tn x nhiu ln vo chiu dy mu o chiu dy ca vng c chiu chm tia in t.

- Nu gi l qung ng t do trung bnh tng cng ca tt c cc tn x khng n hi, I0 l

cng tch phn c ly i vi peak tn hao zero (chnh l din tch ca peak), Itot l cng tch phn ca ton b ph ghi c cho n khong 200 eV quan h ca chiu dycng tch phn ca ton b ph ghi c cho n khong 200 eV, quan h ca chiu dy

mu vi tn x nhiu ln s l:

first-plasmonl It tot

- xc nh t, cn phi bit .zero-loss

ili

=

0

lnIIt tot

nh gi tho c th da trn cng thc

= 0.8E0

silicon

trong tnh theo nm, cn E0 l nng lng ca e s cp (tnh theo eV).

NATuan-ITIMS-2011

CHNG 4: CC PHNG PHP PHN TCH PHc)- Cc tn hao ion ha

- c trng quan trng nht cho phn tch vt liu l cc g ion ha cc lp v bn trong ca

nguyn t, bi v nng lng ion ha l c trng cho cc nguyn t ha hc.

V t th ht hi tt t T hi i h h EELS bit- V nguyn tc, c th pht hin tt c cc nguyn t. Tuy nhin, ni chung ph EELS c bit

nhy vi cc nguyn t nh, v thit din ion ha tng khi nguyn t s Z gim. Tuy nhin,

trong vng nng lng cao, vng ion ha, lm ni bt cc c trng g ion ha, theo thang

cng , cn phi dn thang t vi chc n vi trm ln.

- Trong khong nng lng ln n 2 keV c th lm xut hin cc g K ca cc nguyn t t Li -

Si, cc g L23 i vi cc nguyn t t Al - Sr, v cc g M45 i vi cc nguyn t t Rb - Os.Si, cc g L23 i vi cc nguyn t t Al Sr, v cc g M45 i vi cc nguyn t t Rb Os.

- Mi g ca v su bn trong u c on nng lng cao ko di (tail) m on ny l tn hiu

nn (background) ca cc g tip theo c chng ln trn on ko di .

Th hi h th t hi fit i h - Thc nghim cho thy cng tn hiu nn ny c fit vi hm m:

IB = A.E-r (A v r l cc hng s, E l nng lng tn hao)

C r v A u thay i theo chiu dy ca mu, theo in p gia tc v gc nhn ca ph k. r c gi tr trong khong 2-5, trong khi A c th thay i t ngt.

NATuan-ITIMS-2011

CHNG 4: CC PHNG PHP PHN TCH PHK hiu ca cc g ion ha ng vi cc lp v pha trong nguyn t.

NATuan-ITIMS-2011

Chiu tng ca nng lng ion ha


inner-shell edge Tn hiu ph nn pha nng lng cao high-energy tail

(background)IB = A.E-r

di mi g ion ha lp li l do tn x khng n hi nhiu ln dn n tn hao nng lng.

IB = A.E-r

NATuan-ITIMS-2011

Tr ph nn theo quy lut hm m

CHNG 4: CC PHNG PHP PHN TCH PHd)- Cc cu trc tinh t

- Khi phn gii nng lng cao, v d n 1 eV, c th thu c cc cu trc tinh t gn cc g ion ha. l cc kch thch ca cc e cc lp v bn trong ring r (K, L, M, N,...) chuyn t vng trng thi c bn ca chnh n ln cc trng thi cha b chim trong vng dn, ngha l ion ha cc mc li.

- C hai kiu c trng ca cu trc tinh t: + cu trc tn hao g gn (energy loss near-edge structure, ELNES)

+ cu trc tn hao tinh t m rng (extended energy-loss fine structure, EXELFS)

NATuan-ITIMS-2011

CHNG 4: CC PHNG PHP PHN TCH PH ELNES

- Xut hin do cc chuyn di ca e cc lp v pha trong ca mt nguy t c th ti nhng trng thi cn trng thp nht trong CR.

ELNES c th d mt trng thi (DOS) cn trng trn mc EF v tr ca nguyn t c kch thch.

- ELNES cng lin quan n c nguyn t s, s sp xp, loi nguyn t v lin kt ha hc ca nguyn t m gy ra cu trc kiu ny.

- Ngoi ra ELNES cn cung cp thng tin v d hng trong lin kt ha hc v cu trc di.

EXELFSEXELFS

- Xut hin do sng e c kch thch c bc sng xp x vi khong cch gia cc nguyn t ca mu c chiu truyn qua.

V th th b hi bi t l th t th h i th V th sng ny c th b nhiu x bi cc nguyn t ln cn v c th tr thnh giao thoa vi sng pht ra. S giao thoa c th c tng cng hoc trit tiu, to ra mt phn dao ng no ca cng i km theo vi g ion ha.

EXELFS th d h t h kh h t t i t l EXELFS c th dng phn tch cc khong cch tng tc gia cc nguyn t ln cn gn nht xy dng hm phn b xuyn tm (RDF).

NATuan-ITIMS-2011

CHNG 4: CC PHNG PHP PHN TCH PHe) nh hng ca chiu dy ln cc peak ca plasmon

S v cng cc peak plasmon t ph EELS ca Al sch tng ln theo chiu dy cu mu tinh th. T cng ny, qung ng t do trung bnh i vi kch thch plasmon c th xc nh cnh c.

- i vi cc nghin cu EELS, Ip cn phi nh hn 0.1 I0. - Tuy nhin, i vi cc ht nano c kch thc tiu biu < 100 nm, phn tch EELS vn lun

NATuan-ITIMS-2011

y pc th thc hin mc d cc ht nano l cc nguyn t c nguyn t s Z cao.


C-KDao ng plasmon vi tn x khng n hi nhiu ln

C-K

nh hng ca plasmon (th hin qua mu mng) + tn x lp v K ca

carbon ln hnh dng cu g ion ha li K

to nn cc cu trc tinh t ng vi nhiu ln tn x (n = 0, 1, 2...)( y tnh vi t = 1/2 plasmon-MFP,

NATuan-ITIMS-2011

v gi thit cc peaks plasmon c dng nhn vi Epl = 25 eV)


C-K

T h d hTrng hp mu dy hn: t = 2 plasmon-MFP Dao ng plasmon vi tn x khng n hi nhiu ln hn G ion ha li K c

cu trc gm nhiu cc g con tinh t hn.

NATuan-ITIMS-2011

CHNG 4: CC PHNG PHP PHN TCH PHf)- Thng tin ph nh lng - Cng thun ca ion ha lp v th k: Ik

- S nguyn t c kch thch, N.- rng ca s nng lng ly tch phn cng tn hiu: .

N h h hi h k - Na gc thu thp tn hiu ca ph k: .- Thit din ion ha: (, ).- Khi tn x mt ln: Ik1 = N I0 (,)- Vi tn x nhiu ln: Ik N I0 (,)

D S tuyt i nguyn t trn mt n v din tch m to ra g ion ha th k

trong ph EELS l:

0),(),(I

INk

k

=

D T l nng ca hai nguyn t A v B s l:

),(),( BAA IN

NATuan-ITIMS-2011

),(),()()(

= ABBA

B

A

IN

CHNG 4: CC PHNG PHP PHN TCH PHg)- nh phn b cc nguyn t

- T hp ca EELS v TEM/STEM c th xy dng c cc nh phn b cc nguyn t ca vng b mt mu nghin cu.

B

C N

V.J.KEAST AND M.BOSMAN; MICROSCOPYRESEARCHANDTECHNIQUE70:211219(2009)

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nh phn b thnh phn cc nguyn t ha hc trong hp cht Nitrit-Bo (BN).


V dV d

nh phn b nguyn t ha hc ca cc ht C h th l Co cho thy c lp v b xy ha. nh thu c ch 200kV GIF (G I O Co OGIF (Gatan Image Filter)

O Co O

Disko et al., Proc. M&M 2001, p.1090)

NATuan-ITIMS-2011


NATuan-ITIMS-2011

CHNG 4: CC PHNG PHP PHN TCH PH4) Cc k thut phn tch ph in t khc

a) Ph in th lm xut hin in t Auger (AEAPS)(Auger ElectronAppearance Potential Spectroscopy)

Nguyn l:

S kch thch lp v su bn trong ca nguyn t bi dn n kh nng pht x- S kch thch lp v su bn trong ca nguyn t bi dn n kh nng pht x

khng ch tia X mm m c A. Lng th cp tng cng s tng khi vt qua

ngng ion ha.

- Lng th cp tng cng c o bng AEAPS.

- Dng th cp xut hin bao gm cc A v c t tn x khng n hi ca cc A

hi d i b tchiu su di b mt.

- Dng th cp thay i l php o c bn ca kh nng kch thch ca mt in t

mc li ti mt mc trng trn mc Fermi.

NATuan-ITIMS-2011


b) Ph in t Auger kch thch ion (IAES)) g ( )(Ion (Excited) Auger Electron Spectroscopy)

Nguyn l:

- S kch thch pht x cc in t A cng c th c thc hin bng cc ion (tng t

nh s dng tia X hay ). K thut kch thch mu bng chm ion v pht hin/o phn b nng lng ca cc A to ra k thut IAES.

- Cc ion kh him, cc proton v ht thng c s dng trong k thut IAES.

- Trong ph IAES, bn cnh cc ph tng t nh XPS v AES, cn c nhng peak xut hin t nhng chuyn di trong cc nguyn t hay phn t b phn x khi b mt.

V tnh phc tp ca ph, k thut IAES khng th dng phn tch trc tip, m ch dng trong cc thc nghim vt l c bn nghin cu cc qu trnh Auger xy

NATuan-ITIMS-2011

nghim vt l c bn nghin cu cc qu trnh Auger xy ra trong cc nguyn t b kch thch.

CHNG 4: CC PHNG PHP PHN TCH PHc) Ph trung tnh ha ion (INS)

(Ion Neutralization Spectroscopy)(Ion Neutralization Spectroscopy)

Nguyn l:- Cc ion He+ c chn lc c nng lng trong khong 5-10 eV chiu ln b mt kim loi.

d i b t kh i l t t t i t b t l

(cc ion chm)

- di b mt khong vi lp nguyn t s tng tc vi cc nguyn t b mt ln cn

gn nht hnh thnh nn cc cp nguyn t-ion gi l cc chun phn t b kch thch (excited quasi moleculars, EQM).

- Cc EQM c th c gii phng kch thch bng cch trung ha bi A: cc mc cha y ca ion ( y l He+) nm ngoi khong cc mc c in y ca nguyn t b mt cht

rn xut hin qu trnh chuyn di A trong mt t di ha tr ca CR lp vo l trng Aca lp v b ion ha ion He+. Nng lng vt qu c nhng cho ha tr khc m c pht x ra sau .

- Ph nng lng quan st c phn nh mt trng thi a phng (LDOS) ca cc- Ph nng lng quan st c phn nh mt trng thi a phng (LDOS) ca cc

trng thi b mt CR, nhng li l mt s t tch chp (self-convolution) ca LDOS v cc

xc sut chuyn di qua cc di ha tr. i hi cng c ton hc phc tp gii chp (deconvolution) ph INS(deconvolution) ph INS.

- y l k thut tng i phc tp trong vic x l ph, nn t c s dng.

NATuan-ITIMS-2011

CHNG 4: CC PHNG PHP PHN TCH PHd) Ph dp tt gi bn (MQS)

(Metastable Quenching Spectroscopy)(Metastable Quenching Spectroscopy)Nguyn l:

- K thut ph MQS l s m rng ca k thut ph INS: thay v s dng ion He+ nng lng thp, nguyn t He trng thi gi bn c nng lng thp c dng kch thch pht x . Ghi ch: cu hnh in t ca He: 1s2.

- He trng thi kch thch n He*(21s1) c nng lng ~ 20.62 eV v thi gian sng ~ 2.10-2 s thch hp cho ng dng y.

- Ch to He*(21s1): Gin n kh He p sut cao, dn qua mt ng nh i vo bungCh to He (2 s1): Gin n kh He p sut cao, dn qua mt ng nh i vo bung phng in cathod lnh (plasma c duy tr bng c trng tnh in v t trng): trng cao, cc ion b ngn chn v thc y cc nguyn t He trng thi b kch thch i ra khi vng phng in chm ht pht ra hu nh hon ton ch c He*(21s1).Khi h h t i i b l b t CR ii h t h t b k h th h- Khi chm ht ion gi bn p ln b mt CR s gii phng tnh trng b kch thch.

- C hai c ch u dn n lm pht x A tg t nh INS v thc hin chc nng gii kch thch:

+ Nu mc kch thch trong nguyn t He cng hng vi trng thi trng mc g g y g g g gFermi b mt CR truyn t nguyn t He n b mt ion ha cng hngnguyn t He. Qu trnh trung tnh ho Auger xy ra tng t nh trong INS, v xut hin s t tch chp (self-convolution) ca LDOS.

+ Nu khng xy ra s cng hng trn y, s gii kch thch Auger trc tip c th

NATuan-ITIMS-2011

g y g g y, g g pxy ra khi cc l trng lp v bn trong ca He*(21s1) c lp y t mt trng thi b mt CR v km theo l bt ra kch thch ca ng.t He (gi l qu trnh ion ha Penning). Ch 1 c pht ra ph phn nh s gii tch chp ca LDOS.

CHNG 4: CC PHNG PHP PHN TCH PHe) Ph xuyn ngm in t khng n hi (IETS)

(Inelastic Electron Tunneling Spectroscopy)(Inelastic Electron Tunneling Spectroscopy)- y l cch duy nht theo ngha hon ton c trng b mt m khng cn thc hin trong

mi trng chn khng.

Nguyn l:- Da trn hin tng xuyn ngm in t qua cu trc M/I/M vi lp cch in I dy c vi

nanomt (gi l tip xc xuyn ngm).

- Qu trnh xuyn ngm khng tn hao nng lng xuyn ngm n hi.- Qu trnh xuyn ngm khng n hi xy ra khi xut hin cc trng thi tp ri rc mt

phn cch gia lp kim loi v lp cch in; hoc c cc phn t cc mt phn cch

vi nng lng dao ng mt cch c trng. khi xuyn ngm c th nhng bt mt phn nng lng hoc cho cc trng thi tp, hoc cho cc mode dao ng trc khi xuyn c n in cc i din. qu trnh xuyn ngm b tn hao nng lng khng n hi.

c xuyn ngm, /p tc dng phi ln hn nng lng ca cc trng thi tp hoc ca cc mode dao ng.

- Nu o dng xuyn ngm qua cu trc M/I/M theo in p tc dng, th dng xuyn ngm ny s tng ln khi vt qua c ngng i vi mi trng thi tp hoc mi mode dao ng. D Xc nh c trng thi kch thch ca cc mode dao ng hay trng thi tp.

NATuan-ITIMS-2011


4 1 M 4.1. M u

4.2. Phng php phn tch ph in t

4.3. Phng php phn tch ph photon / ph Rngenph photon / ph Rngen

Ph t l (EDS)1) Ph tia X c trng (EPMA) 2) Ph hunh quang tia X (XRF)3) Mt s k thut phn tch ph photon khc

- Ph tn sc nmg lng (EDS)- Ph tn sc bc sng (WDS)

3) Mt s k thut phn tch ph photon khc- Ph quang ha bng chm ion (IBSCA)- Ph hng ngoi hp th phn x (RAIRS)

Ph t R b t t (SERS)- Ph tn x Raman b mt tng cng (SERS)- Ph pht x quang do phng in ho quang (GD-OES)

4.4. Phng php phn tch khi ph ion4.4. Phng php phn tch khi ph ion

NATuan-ITIMS-2009

CHNG 4: CC PHNG PHP PHN TCH PH1) Ph tia X c trng (EPMA)

Nguyn l:

- Chiu ln b mt mu mt chm tia in t c nng lng 5 50 keV Din ra qu trnh pht x tia X c trng

~5 - 50 keV XChE = h

~ 5 - 50 keV Din ra qu trnh pht x tia X c trng.- Hu nh tt c cc nguyn t c Z 2 (He) u c th pht

x tia X c trng.- Ghi v o s phn b ca lng t tia X c trng pht ra

MUGhi v o s phn b ca lng t tia X c trng pht ra t mu theo nng lng hay bc sng.

- Phn tch s phn b cc lng t tia X c trng theo nng lng hay bc sng. Xc nh c

Tia X c trng XCh pht x.

nguyn t ho hc.

C ch pht x tia X c trng:

32

1Q t h ht ti X t khi b

in t lp li b bt ra

Qu trnh pht x tia X c trng khi bn ph (ion ha) nguyn t bi e:

Tia X c trng c pht ra khi chm eti kch thch cc in t cc lp li ca

NATuan-ITIMS-2011

in t ti kch thchti kch thch cc in t cc lp li ca nguyn t, v dn ti qu trnh chuyn dit cc lp ngoi vo cc lp v bn trong.


- Nng lng ca photon tia X pht ra chnh l chnh lch gia nng lng lin kt Eb ca lp v trong v lp v bn ngoi din ra qu trnh chuyn di:

cng chnh l hiu gia nng lng ion ho ca cc lp v tng ng Do rt xc nh v c trng cho loi nguyn t C s phn tch cc

- Mc nng lng tng ng vi mi lp v in t trong nguyn t ph thuc vo nguyn t khi:

nguyn t ha hc.

vo nguyn t khi:

( )2

2

56.13n

ZEn=

1 do b hiu ng mn chn ( = 0 i vi m hnh l tng). Cc mc tng ng: n = 1 (K-shell), 2 (L-shell), 3 (M-shell).

NATuan-ITIMS-2011

- Tuy nhin cc chuyn di gia cc mc n tng ng vi cc lp v in t khng phi c din ra bt k, m theo mt quy tc ring nguyn l chn lc lng t.

CHNG 4: CC PHNG PHP PHN TCH PH- Cc chuyn di cho php ca in t ti lp v K v bc x tia X c trng tng ng

sau khi ion ha nguyn tsau khi ion ha nguyn t+ Quy tc chn lc lngt cho php xc nh cc chuyn di c php:

N7 ........................

1) n >0 (ngha l ch c cc chuyn di t L K; t M K m khng c

N1 .........................

M (3d l =2 j = 5/2)t M K,... m khng cchuyn di K L; L3 L2).2) l = 1 v j = -1, 0, 1,...

M5 (3d l =2 j = 5/2)M4 (3d l =2 j = 3/2)M3 (3p l =1 j = 3/2)M2 (3p l =1 j = 1/2)

+ Nng lng ca lng t tia X c trng pht x ng vi cc chui vch xc

h (K K ) t h

M1 (3s l =0 j = 1/2)

L3 (2p l =1 j = 3/2)

L (2p l 1 j 1/2)nh (K, K) c tnh gn ng qua nguyn t s Zca nguyn t b ion ha:

L2 (2p l =1 j = 1/2)

L1 (2s l =0 j = 1/2)

2 1 11 3 2E (Z - 1)

(chnh xc hn phi tnh theo cng thc En slide trc) Hai vch b cmNATuan-ITIMS-2011

K (1s l =0 j = 1/2)

CHNG 4: CC PHNG PHP PHN TCH PH- S cc chuyn di K(1,2), K(1-,5), K(1,2) L(1,2), L(1-7,9,10,15,17 ), L(1-6)in t c php ng vi cc loi bc x tia X c trng khc nhau.

Cc vch quan trng nht:K(1,2), K1

Cc vch quan trng nht:

L(1,2)L(1-4)L(1,3)

NATuan-ITIMS-2011

M(1,2), M(1,2), M(1-3), MCc vch quan trng nht: M(1,2), M1, M(1,2), M

Cc vch pht x tia X c trng ca mt s

CHNG 4: CC PHNG PHP PHN TCH PH32

nguyn tNng lng ca tia X pht ra, Ex-ray :

i t l li

1

K: Ex-ray = E1 - E2 K: Ex-ray= E1 - E3L: Ex-ray = E2 - E3 ;.

in t lp li b bt ra

in t ti kch thch

NATuan-ITIMS-2011

CHNG 4: CC PHNG PHP PHN TCH PH- Cc bc x tia X c trng K, K pht x cng vi bc x nn (ph tia X lin tc) khi mtcng vi bc x nn (ph tia X lin tc) khi mt chm e c nng lng ~ 5 50 keV tc dng ln b mt mu.

- C ch ca bc x nn: khi chm e ti c nng lng cao (~ 5 50 keV) tc dng ln nguyn t lp b mt mu gy ra s lch v/hoc hm cc in t ca lp v trong in trng ca ht nhn (chuyn ng gia tc) trng ca ht nhn (chuyn ng gia tc) pht ra bc x in t (tia X) c ph lin tc.

Ph tia X c trng

Ph lin tc (ph nn)

E E

Ph hp th

(ph nn)

NATuan-ITIMS-2011

Eo E

Ph o c l chng chp ca cc ph tia X c trng, hp th v lin tc (nn).

CHNG 4: CC PHNG PHP PHN TCH PH- Nguyn l ca phn tch ph tia X c trng:

* Cc vch bc x c trng tia X c bc sng c nh i vi mi loi nguyn t xc nh C v tr vch xc nh trn gin ph nng lng. Ngha l c tnh

c trng cho nguyn t ho hc (Mosely's law):

Nguyn tc phn tch nh tnh.* Cng ca vch c trng ca nguyn t ph thuc vo nng nguyn t

= 2.481015(Z 1)2 ( E = h & = c/ )

Cng ca vch c trng ca nguyn t ph thuc vo nng nguyn tca n trong mu: IA/IB. Nguyn tc phn tch nh lng.

Nguyn l chung ca vi phn tch tia x c trng trong SEM

* C hai k thut phn tch ch yu, ty thuc vo vic o v phn tch nng lnghay bc sng ca tia X c trng pht ra t mu:y g g p

o s tn sc ca nng lng Ph tn sc nng lng tia X (EDXS: Energy Dispersive X-ray Spectroscopy);

NATuan-ITIMS-2011

o s tn sc ca bc sng Ph tn sc bc sng tia X (WDXS: Wavelength Dispersive X-ray Spectroscopy).

CHNG 4: CC PHNG PHP PHN TCH PHNhng c im cn lu trong phn tch ph tia X c trng (hay EPMA)

Vng th tch tng tc: Vng b ion ha c dng qu l bn di b mt mu, c su m (m). Mt s c im chnh:

- thm su m ca chm e ti

5 to 50 keV

b mt mu ph thuc nng lng

v bn cht b mt. V d:

5 to 50 e

- Chm tia X c trng c pht x t su trong khi, bn di b t

- Xy ra qu trnh tn x n hi v

khng n hi a cp (nhiu ln)

b mt mu.

theo cc hng bt k.

- Din ra qu trnh ti pht x t

th him

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vng c m rng theo chiu

ngang xung quanh chm tia ti.

Cc vng pht x v ng dng


Vng in t th cp (Secondary electron - SE)(SE thng c sinh ra ti ni m chm tia s cp i ti, nhng

Vng e tn x ngc (Back-scattered electron (BSE) (BSE thng c to ra vng su hn di b mt mu

Vng tia X c trng (Tia X c trng thng c to ra ti ni m chm tia s cp i ti. Vng hnh thnh tia X c p , g

ch nhng e no gn b mt mu mi thot ra c v ti c detector SE to nh SE).

vng su hn di b mt mu. in t BSE c nng lng cao hn, nn i c di hn so vi cc in t SE To nh BSE).

gth nm su hn, pha di vng in t BSE) S dng cho phn tch EDX / WDX.

nh SE - cho phn gii khng gian tt nht ca SEM

(k/t h/ h h ii tt)

nh BSE - cho tng phn nh SEM theo Z tt hn (vng pht x khi c Z

l )

Tt nht cho phn tch EDX / WDX(EPMA)

(k/t vng ph/x nh - phn gii tt) cng ln - sng cng cao)

nh BSE c phn gii thp hn so vi nh SE, v thng ch c s dng khi tng phn ha hc (ngha l theo Z).

NATuan-ITIMS-2011

Kch thc cc vng SE v BSE ph thuc vo nng lng ca chm tia ti(M phng qu o ca in t bng phng php Monte-Carlo)


( p g q g p g p p )

Xc sut tn x bin thin theo Z2, v t l nghch vi ng nng ti E0.Cc ng mu m t cc qu o (vt) ca in t BSE.

thm su gim khi Z tng

Low Z High Zkhi Z tng.

S lng ca cc in t tn x ngc (BSE) khng ph thuc nhiu vo nng lng, nhng phn b rt rng theo khng gian.

NATuan-ITIMS-2011

CHNG 4: CC PHNG PHP PHN TCH PH- thm su (trung bnh) ca chm tia e b mt mu:

m = 0.033(Eo2 - Ec2)/

Eo : nng lng ca in t s cp, [keV]E : nng lng ti hn ca lp v in t b kch thch [keV]Ec : nng lng ti hn ca lp v in t b kch thch, [keV] : mt khi ca mu, [g/cm3]

V d: Vi mu Fe (iron, Ec = 7,12 keV), = 8 g/cm3:Eo 15 keV 20 keV 30 keVm 0.7 um 1.5 um 3.5 um

thm su (th tch) cn ph thuc vo loi nguyn t nng, nh hay va

NATuan-ITIMS-2011

CHNG 4: CC PHNG PHP PHN TCH PHV vy vic phn tch lun gp phi vn v iu kin tin hnh phn tch:

+ Vi in p gia tc ln s ci thin c s kch thch ion ho. Tuy nhin li lm tng thm su ca e, v cng gy ra s hp th lng t tia X:

+ Ti u: thng s dng h s qu p U thch hp thng t nht l 2 ln

thm su (th tch) di b mt c phn tch b nh hng bi nng lng chm tia e ti (in th gia tc)

+ Ti u: thng s dng h s qu p Uo thch hp, thng t nht l 2 ln sao cho kch thch i vi tt c cc nguyn t c trong mu.

+ Do hiu ng hp th (lm cho vic nh gi nh lng ph tr nn kh khn hn) v th khng cn thit phi s dng in t c nng lng qu cao

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hn), v th khng cn thit phi s dng in t c nng lng qu cao.+ Khi s dng in p gia tc ln tng cng kch thc ion ha trong phn

tch nguyn t, phn gii theo chiu ngang v chiu su cng u su i.


* in th gia tc ti u ion ho mt lp v no cn phi c mt qu p l: Uo = Eo / Ec 3

ngha l nng lng ca e ti t nht phi gp 3 ln nng lng ti hn ca e b kch thch ca lp v c lin quan.

Khng th c mt iu kin ti u no cng kch thch ion ho cho tt c ccg glp v nguyn t ca mu, m ch c th o c ph ca bao gm tt c cc lng t tia X ch vi duy nht nng lng in t s cp (do cao p ca SEM quy nh)nh).

* Thit din ion ho t cc i khi t c qu p Uo 3.

NATuan-ITIMS-2011

(Xem hnh sau)


Thit din ion ho (Q(E)) gim chm khi h s qu p rt cao > 10Thit din ion ho (Q(E)) gim chm khi h s qu p rt cao, > 10. Trong khi vi qu p rt thp, Uo < ~ 3, khi nng lng ca chm tia e ti

nm trong vng nng lng ti hn (Eo ~ EC), thit din ion ho li gim rt nhanh.

Nh vy c s khc nhau ng k i vi s ion ho do cc l t ti X d h hlng t tia X gy ra, do hunh quang tia X, c th cho rng c s cng hng tia X vi lp v i t th hiin t v v th gy ra hin tng c nh cc i ca thit din ion ho.

* Vi mt h s qu p Uo qu ln th nng lng ion ho ti hn

NATuan-ITIMS-2011

Thit din ion ha (ionization cross-section) Q(E) theo qu p U

g gEc i vi mt lp v li cng nh.


Vi nng lng ca chm tia e ti, EO, c xc inh, v mt chui vch c trng g g , O, , g

ca mt nguyn t c phn tch (xem bng di y, v d Pb-L, -M), th nhy

trn b mt l khc nhau v phn gii khng gian ca php phn tch EDS c

h lchn lc:

NATuan-ITIMS-2011

CHNG 4: CC PHNG PHP PHN TCH PH+ S hp th tia X: T su c vi micromt di b mt mu, ni chu tc

dng ca chm tia e, tia X c trng phi i qua cc lp b mt mu trc khi bay ti detector (EDX) nng lng tia X b hp th khi:

d

- hp th khi cho thy cng tia X

d

gim nhanh theo hm exp v ph thuc vonng lng ca lng t tia X (No), loi vtliu () v chiu dy (d) m n i qua (chnh l su di b mt mu).

- H s hp th khi / l mt hm ca nguyn t s Z ca lp vt liu c hp

Mass absorption coefficient for Zr (Z = 40)

Cc g hp th, xut hin khi nng lng ca tia X b h th d k h th h nguyn t s Z ca lp vt liu c hp

th v nng lng ca tia X:

, trong a l h s hp th A

Na

0 =

hp th do kch thch cc lp v tip theo.

d

NATuan-ITIMS-2011

nguyn t, N0 l s Avogadro, A l khi lng nguyn t.

A .de


Absorption of various x-ray radiation for the Kakanui Hornblende reference standard. The edges indicate actually which elements are present, and the height of the edge being an approximate measure of the element's concentration.

NATuan-ITIMS-2011

CHNG 4: CC PHNG PHP PHN TCH PHThit b:

Sng in tEPMA trong SEM

Knh t th nht

Knh t th hai

Cun qut chm tia e-(SEM) trn b mt mu

HV quang hcb mt mu

Detector e-

Microamperko dng qua mu

NATuan-ITIMS-2011

K thut WDXS thng khng hay ghp ni vi SEM, trong khi k thut EDXSthng hay c kt hp vi SEM.


EDXS/EDS trong SEM

NATuan-ITIMS-2011

Bung mu

CHNG 4: CC PHNG PHP PHN TCH PHThit b: Ngun in t (e-gun) pht x nhit

Phng trnh Richardson-Dushman cho mt dng in t pht x:

LaB6 tip

=kTTAj exp.. 2

6 p

A: Hng s Richardson (Acm-2K-2) - ph thuc vt liu pht x (A = 4mek2/h3 ~ 1202 mA/mm2K2 trong m khi lng in t e in tch nguyn t(A = 4mek /h 1202 mA/mm K , trong m khi lng in t, e in tch nguyn t, h l hng s Plank, k l hng s Boltzmann (1.38066 10-23J/K)

: Cng thot (work function) ; T : Nhit .+ Vt liu c cng thot cng thp, im nng chy cng cao cng tt.

C d h ti ht l+ Cng dng ca chm tia e- pht x cng cao, sng cng ln

NATuan-ITIMS-2011

(Nhit nng chy)


Thit b:

Bng: Cng thot v hng s Richardson ca mt s vt liu khc nhau

Material A.b*) (A.cm-2 K-2) Material A.b*) (A.cm-2 K-2)

Molybdenum 4.15 55

Nickel 4.61 30

Iron ~ 4.7 26

Platinum ~ 5.7 32

Tungsten 4.2 60

Ba on W 1.56 1.5

Tantalum 4.12 60

Tungsten 4.54 60

Barium 2.11 60

Cs on W 1.36 3.2

Th on W 2.63 3.0

Thoria 2.54 3.0

Cesium 1.81 160

Iriduim 5.40 170

Platinum 5.32 32

BaO + SrO 0.95 ~10-2

Cs-oxide 0.75 ~10-2

TaC 3.14 0.3

Rhenium 4.85 100

Thorium 3.38 70

LaB6 2.70 29

theoretical: 120.2 (b = 1)

*) b l h hi h h t li V h Ri h d A th ht l "h h h " kh i t ht

NATuan-ITIMS-2011

*) b l h s hiu chnh vt liu: V hng s Richardson A - thc cht l "hng s ha hc" ca kh in t pht x nhit (c lin quan n th ha v cng thot) - khi vng nhit cao khc vi khi vng nhit rt thp ( c coi nh l thuyt, A = 120 amp./cm2 K2, ngha l coi b = 1).

N i t ht t

CHNG 4: CC PHNG PHP PHN TCH PHThit b: Fieldemitter Ngun in t pht x trng

(Field emission guns - FEGs)

Phng trnh Fowler-Nordheim cho mt dng pht x:

workfunction

vacuum level

o

t

e

n

t

i

a

l

=

FB

FAj

1.5

exp.2

in trng E

Trong :

A = 1.510-6; B = 4.5107; F >> 108(V/m)

tunnelingfunction eV

conduction band

p

barrierFermi level

F >> 108(V/m).

distance

FieldF V/cm

S gim cng in trng ngoi chn khng theo khong h khi i khi b t ht

Hnh dng mi nhn to ra s tp trung mt ng sc in ln -in trng cao

Lu : S pht x trng xy ra khi cng in trng F >> 108V/m. Cn phi c chn khng cao trnh phng in h quang nh mi nhn.

cch khi i xa khi b mt pht x. in trng cao.

V bn cht s pht x trng l s xuyn ngm ca in t qua ro th l cng thot, nn ng c trng I-V (current-voltage) khng tuyn tnh.

Kch thc vt chm tia rt nh v in trng cao gy ra s xuyn ngm ch gn u mi nhn.NATuan-ITIMS-2011

Pht x Schottky: ngun pht x nhit c tr gip bi in trng


Cng thot ph thuc vo nhit T v in trng F theo cng thc:

21

50 )(108.3; mV

eeFe == Cathode hot ng nh mt thit b pht nhit vi nng lng EA = 0 - .

000 )(108.34

;4

mVe

( )V d: i vi F = 1108 V/m, = 0.38eV.Ly T = 1750 K, th kT = 0.15 eV, t d t th l tmt dng tng theo quy lut:

j/j0 = e0.38/0.15 = 13.

Khi F cao hn ng k so vi 1108V/m, g ,phng trnh trn khng cn ph hp na v dng xuyn ngm tr nn ng k.

NATuan-ITIMS-2011


Dng pht x trng ca cc du nano

Hnh vi pht x trng ca ng nano cacbon (CNT). Hnh nh cho thy biu Fowler-Nordheim (FN) tng ng

S ph thuc ca dng pht x trng ca dy nano v mi kim nano ZnO vo cng in trng (E). th nh km theo l th ng ln(J/E2) 1/E (ng

NATuan-ITIMS-2011

tng ng. th nh km theo l th ng ln(J/E2) 1/E (ng lin nt l kt qu m phng theo phng trnh FN.

CHNG 4: CC PHNG PHP PHN TCH PHSo snh phm cht gia cc ngun in t khc nhau

*

(flashing)

NATuan-ITIMS-2011

(flashing)


Thit b vi u d in t EPMA (Electron Probe MicroAnalyser)

Thit b: c lp t km theo SEM

NATuan-ITIMS-2011


Thit b:

Yu cu khi tin hnh phn tch EDS trong SEM

Cn c c nhng iu kin tt nht:

B mt mu phng khng b nhim bn (lu khng ph Au m s dng C thay th).

Mu phi ng u ni phn tch (nghi l vng tng tc ca e s cp vi Mu phi ng u ni phn tch (nghi l vng tng tc ca e s cp vi b mt mu).

Phn tch c tin hnh theo phng ngang ca b mt.

Tc m cao (nhng thi gian cht < 30%)

H s qu p khong Uo = Eo/Ec > 1.5 2

NATuan-ITIMS-2011

CHNG 4: CC PHNG PHP PHN TCH PHThit b: DetectorDetector: Ghi/o tia X trong k thut EDS/WDS-SEM

- C 2 kiu ghi/o-phn tch tia X:+ Ghi ph cng tia X theo nng lng: EDXS/EDS. S ( ) y s dng detector bn dn Si(Li) nhy vi nng lng ca cc lng t photon.

+ Ghi/o theo bc sng ca bc x tia X: WDXS/WDS.

Kiu ny i hi phi c b lc n sc (monochromator) v ng m t l (propotional counter).

- u im ca kiu o/ghi-phn tch WDS so vi kiu EDS:+ WDX cho phn gii theo nng lng tt hn nhiu so vi kiu EDS.+ Hn ch rt nhiu sai s do s chng chp ca nhiu peak+ Hn ch rt nhiu sai s do s chng chp ca nhiu peak

(thng hay gp trong kiu phn tch EDS.+ Nhiu nn (background noise) thp hn, cho php phn tch nh lng chnh xc hn

so vi kiu phn tch EDS.so vi kiu phn tch EDS.- Nhc im (???):

+ Phn tch WDS mt nhiu thi gian hn phn tch EDS.+ Phn tch WDS ph hu mu mnh hn (v i hi dng chm tia e- cao hn) do

gy nhim bn bung chn khng nhiu hn.+ Gi thnh phn tch WDS cao hn.

NATuan-ITIMS-2011

CHNG 4: CC PHNG PHP PHN TCH PHSo snh ph EDS v WDS

Ph EDS ca BaTiOEDSBa-L + Ti-K

Ph EDS ca BaTiO3EDSBa-L1

Ba-L1

Ba-LBa-L2

Ti-K

Ti-K

WDS

Ba-LTi-K1,2

Ba-L1

Ph WDS ca BaTiO3

WDSTi-K1 Ba-L2

Ba-L1

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Ba-L1


Thit b:Qu trnh ghi/o v x l tn hiu tia X c trng trong phn tch EDS

NATuan-ITIMS-2011


Detector bn dn Si(Li) s dng cho phn tch EDS

n b tin khuch i

in cc Au tip

(mng Au ~ 200 nm)

xc mt di)

B mt hng bc x c ph mng Au dy ~ 200 nm (in cc tip xc pha trn)

NATuan-ITIMS-2011

( p p )

CHNG 4: CC PHNG PHP PHN TCH PHDetector bn dn Si(Li) s dng cho phn tch EDSThit b:

Lng t tia X gy ra qu trnh ion ho Si hnh thnh cp e-h. nng lng tia X c chuyn i thnh in tch. Nng lng tia X c trng t l vi dng in to thnh. B phn tch a knh (multichannel analyzer), chuyn i nng lng tia X thnh tn hiu in.

V d v tn hiu c to ra t detector Si(Li) i vi

G, khng cn t ( h lf)

Mn K

Mn K

( )tia X c trng ca Mn-K v -K.

Nn ca b tin K

Cc peak khng cn quan tm (escape peaks)

quan tm (shelf)(

t

h

a

n

g

l

o

g

)

Mn K

Hiu sut chuyn i nng lng tia

Peak hunh quang ca bn thn Si

(escape peaks)

C

o

u

n

t

s

Hiu sut chuyn i nng lng tia X thnh in tch tng ng l 3.8 eV/cp e-h trong mt ph nn trung bnh gm cc nhiu in t v cc i t h hi kh

NATuan-ITIMS-2011

Nng lng

in tch nhiu khc.

phn gii ~ 130 eV/vch Mn(K).

CHNG 4: CC PHNG PHP PHN TCH PHDetector bn dn Si(Li) s dng cho phn tch EDSThit b:

WD (Working Distance): Xc nh khong cch gia u cng ca ming cc (trong h quang hc ca chm tia e) v bmt mu. Thng detector EDX c lp t sao cho nhn thy b g p ymt mu di khong cch lm vic WD khng i.

TOA (Take Off Angle): Xc nh gc gia trc tinh th ca detector EDX v mt phng mu. Gc TOA kh d nm trong khong c gii hn bi v tr ca cng EDX trntrong khong c gii hn bi v tr ca cng EDX trn SEM v thng khng i, mc d ngi s dng vn c th lm bin i gc ny khi nghing gi g mu dng trong trung hp phn tch cc nguyn t nh (cn gc TOA ln hn hn ch hiu ng hp th do cu hnh bTOA ln hn hn ch hiu ng hp th do cu hnh b mt ca mu).

NATuan-ITIMS-2011


Detector bn dn Si(Li) s dng cho phn tch EDSThit b:

Single-element Si(Li) Detectors

.

NATuan-ITIMS-2011


Ghi/o v x l tn hiu tia X c trng trong phn tch WDS

NATuan-ITIMS-2011


Wavelength Dispersive Spectroscopy (WDS)Thit b: g p p py ( )

NATuan-ITIMS-2011


Wavelength Dispersive Spectroscopy (WDS)

NATuan-ITIMS-2011


Detector tia X kiu CCDThit b:

Detector tia X kiu CCD

NATuan-ITIMS-2011

Large-Area CCD X-Ray Detector


NATuan-ITIMS-2011

CHNG 4: CC PHNG PHP PHN TCH PHMt SEM c bit vi vi u d in t vi trang b

t d t t EDS t d d t t WDSThit b:

mt detector EDS v mt dy cc detector WDS.

NATuan-ITIMS-2011


S hi/ ti X t EDS WDSS ghi/o tia X t hp c hai k

thut o ph

EDS WDS

p

EDS v WDS

trong SEM

NATuan-ITIMS-2011


EDS trong TEM

Detector

NATuan-ITIMS-2011

CHNG 4: CC PHNG PHP PHN TCH PH Thng tin t Ph EDXS

Phn tch EDS/WDS nh tnh:

Xc nh cc nguyn t ha hc

NATuan-ITIMS-2011

CHNG 4: CC PHNG PHP PHN TCH PH Thng tin t Ph EDXS

Phn tch EDS/WDS nh lng:

Xc nh t phn cc nguyn t ha hc

T s nng

Hiu chnh ZAFZ : nguyn t s: hiu chnh i vi cc tnh cht tn x khng n hi khc

h d kh h i t t b h t tnhau do s khc nhau gia nguyn t s trung bnh trong mu v trong mu chun.

A : hp th: hiu chnh /v nhng sai lch do hp th tia X.

NATuan-ITIMS-2011

F : hunh quang tia X: hiu chnh /v s sai lch do hunh quang tia X.


X-ray Mapping Thng tin t Ph EDXS y pp g

NATuan-ITIMS-2011


4.1. M u

4.2. Phng php phn tch ph in tg p p p p

4.3. Phng php phn tch ph photon / ph Rngenph photon / ph Rngen1) Ph tia X c trng - EPMA (EDS/WDS)1) Ph tia X c trng EPMA (EDS/WDS)2) Ph hunh quang tia X (XRF)2) Ph hunh quang tia X (XRF)3) Mt s k thut phn tch ph photon khc

Ph t h h h b h i (IBSCA)- Phn tch ph quang ha bng chm ion (IBSCA)- Ph hng ngoi hp th phn x (RAIRS)- Ph tn x Raman b mt tng cng (SERS)- Ph pht x quang do phng in ho quang (GD-OES)

4.4. Phng php phn tch khi ph ion

NATuan-ITIMS-2011

CHNG 4: CC PHNG PHP PHN TCH PHPhn tch nguyn t vt c tng cng trong SEM - K thut ph XRF

- Nhm tng cng kh nng vi phn tch cc vt nguyn t trong cc thit b SEM, a thm vo mt ng pht vi chm tia X c gn t hp cng vi detector EDS.

- Nguyn l:S ht h t ti X (h h ti X) d i t d k h th h b ti XS pht x photon tia X (hunh quang tia X) di tc dng kch thch bng tia X

XRF

X ray

- u im:+ Phn tch c bn nh lng hu ht cc nguyn t trong bng tun hon.+ Thi gian phn tch nhanh

X rayE = h

+ Thi gian phn tch nhanh+ Khng cn ph hy mu+ o c cc mu trng thi rt a dng: rn, lng, bt, polymer, mng mng Nhc im:

NATuan-ITIMS-2011

- Nhc im:+ Ch yu phn tch nh tnh, c bit l phn tch "vt" (pht hin c mt nguyn

t vi hm lng rt thp; c th nh lng chnh xc ch trong mt s trng hp).


Phn tch nguyn t vt c tng cng trong SEMPhn tch nguyn t vt c tng cng trong SEM

S b tr bn trong SEM

Detector EDS

ng pht vi chm tia X

NATuan-ITIMS-2011

S ca ng pht tia X tiu im nh kt hp vi mt detector EDS gn trong SEM Hitachi S 3000 NH

CHNG 4: CC PHNG PHP PHN TCH PHPhn tch nguyn t vt tng cng trong SEM

Detector EDS

h ing pht vi chm tia XX-Beam

NATuan-ITIMS-2011

S ca ng pht tia X X-Beam kt hp vi mt detector EDS gn trong SEM Hitachi S 3000 NH


Phn tch nguyn t vt tng cng trong SEM

Ngun tia X X-Beamc gn vo SEM

H X-Beam Micro-EDXRF

g y g g g

c gn vo SEM

X-Beam

X-Beam on FEI Quanta 600NATuan-ITIMS-2011

X-Beam on JEOL JSM-7000 X-Beam on Hitachi S-3400


Detector bn dn Si(Li) s dng cho phn tch XRF

Detector nhiu phn t (Multi-element Si(Li) Detectors) Mi detector phn t c thit k mt cch c bit s dng cho nhng trng hp c th ph hp vi kch thc ng s nh hng tinh th ca s ni thng vhp c th, ph hp vi kch thc ng, s nh hng tinh th ca s, ni thng v bt kn chn khng.

Detector 13-phn t etecto 3 p tdng phn tch hunh quang tia X (XRF) phn gii cao v ph hp th tia X p p (XAS) tc cao.

Gm 13 vin tinh th Si(Li) c din tch 50mm. Sp xp chm li gn nhau trn b mt cong. Cc ca s mng bng DuraBeryllium(TM). C tnh chn lc tt khi s dng i vi tng ci

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C tnh chn lc tt khi s dng i vi tng ci(no cross-talk).

C cc b tin K hi phc khng ng b. phn gii /v nguyn t n: < 145 eV


Multi-element Si(Li) DetectorsDetector bn dn Si(Li) s dng cho phn tch XRF

Multi-element Si(Li) Detectors

Detector 7 phn t dng phn tch hunh quang tia X Detector 6 phn t dng phn tch hunh quang tia X (XRF) phn gii cao v ph hp th tia X m rng cu trc tinh t (EXAFS) tc cao:

- Gm 7 tinh th Si(Li) 7 x 80mm - c b tr tp trung theo gc khng gian

S dng loi ca s DuraBeryllium(TM) mng

phn x ton phn phn cc (SR-TXRF).- Gm 6 tinh th Si(Li) 6 x 30mm- Sp xp theo hng thng- S dng c s DuraBeryllium(TM) mng 8m- C tnh chn lc tt khi s dng tng tinh th ring r

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- S dng loi ca s DuraBeryllium(TM) mng- C tnh chn lc tt khi s dng tng tinh th ring r- C cc b tin khuch i hi phc khng ng b- C phn gii i vi nguyn t n


4.1. M u

4.2. Phng php phn tch ph in t

4.3. Phng php phn tch ph photon

4.4. Phng php phn tch khi ph ion4.4. Phng php phn tch khi ph ion1) Khi ph ion th cp tnh (SSIMS)

2) Khi ph ion th cp ng (SIMS)

3) Khi ph trung ha th cp va chm in t (EI-SNMS)

4) Khi ph trung ha th cp laser (Laser-SNMS)

5) Ph t R th f d (RBS)5) Ph tn x ngc Rutherford (RBS)

6) Ph tn x ion nng lng thp (LEIS)

7) Cc k thut khc lin quan n phn tch ion) Cc t ut c qua p t c o

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CHNG 4: CC PHNG PHP PHN TCH PH Nguyn l chung:

- Bn ph b mt CR bng cc ion dng () Cc lai ht/bc x thot ra:

+ Nguyn t trung ha (hin tng phn x)+ |

+|

+ Ion dng th cp ' v ion m th cp '+ Nguyn t b kch thch + Photon (tia X, tia UV)+ e Auger; e th cp

- o v phn tch cc ion ' v ' bng ph k khi lng (gi l khi ph k) Thu c gin ph khi lng ca cc ion th cp: l cc peaks c trng cho ngun ion v b mt b b h Ph t h t h ht t b t h ht b d h t b tbn ph. D Phn tch c tnh cht, cu trc ca b mt hay cc cht bm dnh trn b mt.

- Cc speaks c th c xc nhn ca chnh vt liu , t cc cht bm dnh hay cc tp cht trn b mt mu, hoc cc cht c a vo hp th c ch tm ln trn b mt.

- Trong cc k thut khi ph, cc ht nng dng bn ph thng l ion Ar+ c nng lng ~ 1 - 15 keV.

C l i khi h k th d Khi h i th t h (SSIMS) (SIMS)- Cc loi khi ph k thng dng gm: Khi ph ion th cp tnh (SSIMS) v ng (SIMS), Ph tn x ngc Rutherford (RBS), Ph tn x ion nng lng thp (LEIS),...

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Ph lcPh lcPh lcPh lc(tm hiu thm)(tm hiu thm)

Cc k thut thc nghimCc k thut thc nghimCc k thut thc nghim Cc k thut thc nghim trong ph tn x neutrontrong ph tn x neutron

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Ph tn x neutronPh tn x neutron

Hy th ci liHy th ci li

Nghin cu dao ng mng th no?

Hy th ci li ...Hy th ci li ...

... nguyn l ca cc thc nghim tn x... nguyn l ca cc thc nghim tn x

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18

1020

X-ray electromagnetic electromagnetic Cc neutron

1016

1018

ultraviolett

radiationradiationneutron kh k d

1014

/

H

z

visible

infraredneutronsneutrons

phonon-phonon-

1012

far infrared

microwaves

frequenciesfrequencies

hopping-hopping-

108

1010

Khong cch gia cc nguyn t

Khong cch gia cc nguyn t

10-10 10-8 10-6 10-4 10-2 10010

/ mNATuan-ITIMS-2011



Ph k ba trc l cch nhn trc tip ca tam gic tn x:

Ph k ba trc (Three axes spectroscopy)

kfB lc sc

Muki

QQ

detectorB phn tch

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Ph k ba trc PUMA t ti FRM-II

Ph k ba trc (Three axes spectroscopy) Khe vo c th bin i

B chn la

B lc scB lc sc (monochromator)

(hi t kp)

Bng mu

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B phn tch/ detector



( ) ( ) ( ) += kiii SbbSS 1 ),()()( QQQC s ca tn x neutron

Hm tn x kt hp ring phn (coherentcoherentpartial scattering) trn y l php bin i i

(r,t)r k

( ) ( ) ( ) +=i k

cohkii

incinc SbbSS ,,4,),()()( QQQ

partial scattering) trn y l php bin i Fourier ca hm tng quan cp KG-TG (space-time pairpair--correlationcorrelation) i vi cc ht kiu i v k

i(r,0)(0,0)

ht kiu i v k.

( )( ) ( )( ) += j j Tjjki tdNtG RrrRrrr 01),(),(

(r,t)

j jNto ra s chuyn ng tp thchuyn ng tp th

((collective motion)collective motion)

( ) ( )1( ) ( ) ( ) ( ) dtdtbbeN

S ticoh rRRrQrQ rrrrr rr = )0((2

1,

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Tn x neutron khng n hi t cc phonon( )Q jhC s ca tn x neutron

( ) ( )

( ) ( ) ( ) =

q

qrqeQQ 2kj

coh )iexp(Wexpmjb

N4),(S h

S bo ton nng lng:

( ) ( ) ( )

+++ +

gqgQqq

gqgQqq ,jj,jj 1nn

ki

kfBo ton chun xung lng (quasi-

1)exp(

1j,

j,

=

kT

nq

q h

i

QQuy lut Quy lut

lng (quasimomentum)

gyy

chn lc s chn lc s phn ccphn cc q

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0 qj-qj



Cc neutron nhy vi cc thnh phn ca s dch chuyn song song vi s

C s ca tn x neutron

truyn xung lng Q

Lut bo ton chun xung lng (quasi-momentum) gip cho vic quan st cc phonon ngang.

g

Q Qe

qg q

eg

q

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S tn sc phonon

S tn sc phonon ca Nd2CuO4

PINTSCHOVIUS et al. (1991).

Nd2CuO4

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Ph tn x neutronPh tn x neutronLA-Phonon

q = (2/3 2/3 2/3)S tn sc phonon ca Hafnium lp phng tm khi (bcc)

S tn sc phonon

TA-Phonon q = (1/2 1/2 0)

Trampenau et al. (1991)

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S tn sc phonon ca thch anh beta (-quartz)S tn sc phonon

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Mt phonon

- Thm d cc phonon u trong khng gian o (nghch) ?

Nhng cng c cho rng

( ) ( ) ( ) ( ) ( ) +++= qrqeQQ 2 1nn)iexp(Wexpjb)(S h

l mode mm (quartz-softmode) ca thch anh:

( ) ( ) ( ) ( ) ( )

+++= + g qgQqqg qgQqqq qrQ ,jj,jjkjcoh 1nn)iexp(WexpmbN4),(S

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- Mt trng thi phonon:

G()d = S cc dao ng mng vi tn s trong khong gia

Mt trng thi

G()d = S cc dao ng mng vi tn s trong khong gia v + d

( ) ( ) =j

jGq

qjq

Xc nh nng lng tch tr trong h phonon: nhit dung v cc i lng nhit ng khcNATuan-ITIMS-2011

CHNG 4: CC PHNG PHP PHN TCH PHPh tn x neutronPh tn x neutron

- Ni nng v nhit dung: ( ) = 0 kToPh dG1)exp(EE hh

h

Nhit ng lc hc ca phonons

=0

2

kT

kT2

V d)(G

1e

ekT

kch

hh

Nhit dung ca thch anhMt trng thi ca thch anh (quarzt - SiO2)

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Tn x khng kt hp t cc phonon:

C s ca tn xneutron

( ) ( )kj

incinc Wm

jS

q

qeQQ

= 2exp8),(

2h

( ) ( ) ( ){ }jjjjj

nn qqqqq

+++ 1L t tt Ly tng qua tt c cc trng thi phonon

( ) ( ) ( ) ( ) ( ){ } 2

inc 1jqeQh

( ) ( ) 12j 2qe

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Chuong4 Cac Phuong Phap Pho 2011