Chuong 2. Phuong Phap Nhieu Xa Tia X (1)

8/12/2019 Chuong 2. Phuong Phap Nhieu Xa Tia X (1)

1/56

1

Incident beam

Diffraction X rays

X-ray detector

Crystallinesolid

Lead screen

10,000-40,000 volts

X-ray tubesource

X rays


2/56

2

Trong scc phngphp vt l nghin cucu to,phngphp nghin cucu trc bng tia X (tia Rnghen) l phngphp quan trngv hiuqunhtv n cho php xc nhvtrcacc nguyn ttrong tbo cbn,tcl xc nhcdi lin ktv gc lin kt.

i tngnghin cu rngri: protit, phccht,phn tADN,ARN, cc khong vt,cc loivtliul itngcanhha hc,sinh hc,vtl hc,vtliuhc,achthc

Phn tch cutrc bngtia X gm2 giai on.Giai on1 lxc nhcc thng scamngtinh th,tnh ixngcamngtinh thv mtsdkinkhc c lin quan.Giai on 2 l xc nh taca cc nguyn t trong khnggian tinh th,di lin kt,gc giacc lin kt.

1. M u


3/56

3

Tia X v tia gama- Ging nhau: u l cc bc x in t c bc sng ngn,nnglngln.- Khc nhau: Tia X thngctora trong qu trnh tngtcgiamtchm tia electron vicc electron canguyn t,tia

csinh ra bisthay ibn trong htnhn nguyn t.

2. S lc v tia X


4/56

4

Cc thng s v tia X

Tia X l cc bcxin t sng ngnc sinh ra bis

bnph cc bia kim loibngcc chm electron nnglng

cao hocc tora trong qu trnh chuyndchelectron

obital bn trong (obital d hay f) canguyn t.

Nnglng: 200eV - 1MeV

Bcsng: 10-5 - 100

Bcsng thuntincho nghin cunhiuxtia X l 0.1 -

25 (khongcch giacc nguyn ttrong tinh th~ 2)

2. S lc v tia X


5/56

5

Wilhelm Conrad Rntgen tm ra tia X vo nm 1895. Nm1901ng c trao gii Nobel Vt l. Nm 1995 cng ty GermanFederal Mail pht hnh con tem tngnhncng lao caW.C. Rntgen.

Lch s pht hin tia X

2. S lc v tia X


6/56

6

Tia X c to ra bng cch bnph mtchm electron vo mtbiakim loi (


7/56

7

Phpht xtia X cchia lm 2 loil phlin tcv phvch.

Phlin tcxuthinkhi thtln ngpht tia X nhhnth

kch thch. Khi ,nnglng(ngnng)cacc electron cha

mxuyn vo cc lpK, L, Mnmsu bn trong, do

mtphnnng lngchuyn thnh nhitnng lm nng imcc,phncn lichuynthnh nnglngbcxint(tia X).

Khi tngdn thV t ln ngpht tia X tnmtgi trno

, trn ph s xut hin mt s vch c cng ln r rt,

nghal xuthinphvch. Thbtuxuthinphvchgil ngngkch thch Vkt.

3. Ph pht x tia X


8/56

8

Phvchxuthinkhi inthp tln ngpht tia X lnhnngngkch thch.

Khi ,nnglngcaelectron lnmxuyn vo cc lpelectron st htnhn (cc lpK, L, M), lm btcc electron cc lpny ra khinguyn t,tonn trngthi kch thch, trong

cc lpK, L, Mkhuytcc electron.Cc trngthi kch thch ny khng bn,hunhngay lptcccelectron cc lpbn ngoi snhyvo chimcc chkhuyt,qu trnh km theo sgiiphng ra mtnnglngdidngsng int(tia X).

Thcnghimcho thyphpht x tia X thnggm2 vch ccngmnhl Kv K.

3. Ph pht x tia X


9/56


10/56

10

Ph vch tia X Electron ti c nng lng ln lm bt

mtelectron lptrong v lm nguyn tbiabkch thch vimtltrng.

Khi ltrngny clm ybi1 electronlpngoi th 1 photon tia X cpht ra.

Cc photon ny c nng lng bng hiuhai mc nng lng v c trng cho kimloiclm bia.

Phcacc photon ny l cc pic nt chngln phlin tc.

Thtngtcchlm thay igiihnbcsng ngncaph lin tc,khng lm thayibcsng vchctrng.

Cngcavchctrngphthucvothtngtcv cngdng cangpht

3. Ph pht x tia X


11/56

11

K hiu vch tia X c trng

Nultrng lpK v c lm ybimtelectron trn lpL, M, th ta c dy vchK, K,

Nu ltrng lpL v clm ybimtelectron trn lpM, N, th ta c dy vchL, L,

3. Ph pht x tia X


12/56

12

K hiu vch tia X c trng

C hai vchK l K1 v K2 rtxt

vinhau v c cngtl2:1. Tlcng

K1: K2: K = 10:5:2

3. Ph pht x tia X


13/56

13

Gi tr bc sng vch tia X c trng

c cc tia X vikhc nhau, ngita dng cc kim loikhcnhau lm anot. Miquan hgia, X cm tbinh lutMoseley: 1/ = R(Z-1)2(1-1/n2): bcsng; R = 109737 hngsRydberg; Z: shiunguynt; n l mtsnguyn, n = 2, 3 ivivchKv Ktngng

Nguyn t Z K1 (nm) K2 (nm) K Ngng VCr 24 0,228970 0,229361 0,208487 5950

Fe 26 0,193736 0,193998 0,193604 7100

Co 27 0,179026 0,179285 0,178897 7700Ni 28 0,165791 0,166175 0,1500 8300

Cu 29 0,154184 0,154439 0,1544056 9000

Mo 42 0,071073 0,071359 0,070930 20000

Ag 47 0,055941 0,056380 0,0497 25600

3. Ph pht x tia X


14/56

14

Khi tia X i vo mi trng vt liu s c cc hin tng: S

khuychtn, Hiungquang in,Pht hunhquang v S tothnh cpelectron - positron. Ktqul cngtia X gim

dI = -Idx I = Ioexp(-x)

Iov I l cngtia ti,tia l; x l bdy cavtliu; l hshpth

4. Ph hp th tia X


15/56

15

Ph hp th tia X

Nhn vo ph hp th tia X ta thy:

Khi bctia X sng gim(nnglngtng)th khnngmxuyn catia Xtngdn,hpthgimdn.

Khi gimnmctia X c thmxuyn vo cc lpelectron trong cng(K, L, ) v lm bt cc electron cacc lp ny th hp th tng tngt.ychnh l b in hpth.

Khi vtqu bin hpth,hpthgimdnv nnglngcatia X qu ln,tia X c thmxuyn qua mi trngvtlium khng bhpth.

4. Ph hp th tia X


16/56

16

Tia X n scDng tmkim loic bin hpththch hphpthbcxK

v cho bcxKiqua

Bc x Vt liu lc dy (mm) truyn qua

ca K(%)Cr - K V 0,018 50

Fe - K Mn 0,016 46

Cu - K Fe 0,018 44

Cu - K Ni 0,021 40

Mo - K Zn 0,108 31

Dng bnsctinh th: Mttinh thbitnhhngsao chochnhiuxtia Km khng nhiuxtia K.

4. Ph hp th tia X


17/56

17

Tia X n sc

Trong nghin cunhiuxtia X thngsdngtia Kcacacc kim loikhc nhau (cbitl kim loiCu). V cc vchKcnnglngln,khng bhpthbivtliunghin cu,nsccao.

Bin hp th caNi iviphphtxcaCu.

4. Ph hp th tia X


18/56

18

Phng trnh dng hm sinSng tun hon theo thi gian:

= Asin(t + ) vi

Sng tun hon trong khng gian:

= Asin(kr + ) vi

A: Bin sngtn s gc = 2f = 2/T

T l chu k theo thi gian; f l tn s: l lch pha

A: Bin sngS sng k = 2/: l chu k trong khng gian-bc sng: l lch pha

5. Phng trnh hm sng


19/56

19

Phng trnh dng hm phc

Sng tun hon trong khng gian:

= Aeikr vi

Cng thc le:

= Aei= A(cos+ i.sin)

A: Bin sngk: vect sng c chiu l chiu truyn sng,

|k| = 2/: chu k trong khng gian-bc sngr: vect ta

Sng chuyn ng (sng phng) c biu din bng mt vect k.Nng lng ca sng t l thun vi bnh phng ca |k|.

5. Phng trnh hm sng


20/56

20

Nh bit: cc ht vi m l cht lng tnh snght

Tnh ht:biudin tnh chtgin oncavtcht. Khi htchuynng th n mang theo mnh c nng lng v khilng

Tnh sng: biu din tnh cht lin tc ca vt cht. Khi htchuyn ng th n ch mang theo nng lng m khngmang khilng

Trong chng ny chng ta s xt hin tng tinh th lm

nhiuxbcxtia X. Tuy nhin cc ktqu thu ccngc thdng chung cho nhiuxelectron, ntron,

6. Nhiu x tia X


21/56

21

Phnx; tn x; giao thoa?

Phnx:Tia tibphnxbimtmtphng; gc tibnggc phnx; nnglngcngnhbcsng khng thay i

Tn x:Tia tiva chmvimtimvtchtno ; imvtchtny trthnh mtngunbcxthcppht bcx(tia tn x)ra cc hngkhc nhau. Tia tn v tia tic nnglngc thbngnhau (tn xnhi)hockhc nhau (tnxkhng nhi).

Giao thoa:L hin tngcnghpsng. C giao thoa tngcng (cc sng ti cng pha) v giao thoa trit tiu (ccsng tingcpha)

6. Nhiu x tia X


22/56

22

Nhiu x l g, c hai cch hiu: Tp hp cc phnxcbit t mt hmtphng nguyn t

song song trong tinh thmboiukingiao thoa tngcng. Tphpcc tn xnhicbittcc imkhc nhau ca

tinh thmboiukingiao thoa tngcng

Kt qu: Thu c ccchm tia nhiu x theocc hng xc nh, ctrngcho tinh th. Cc tia

nhiuxny c thcghi li di dng nhnhiu trn phim hocc v thnh gin nhiux.

6. Nhiu x tia X


23/56

23

sin2

nd

Hin tng nhiu x tia X cquan st u tin bi Max VonLaue (18791960, gii thngNobel Vt l nm 1914) vo nm1912

Hin tng nhiu x tia X cgii thch bi hai cha con gianh Bragg nm 1913

(Wiliam Henry Bragg (cha), 1862-1942,v Wiliam Lawrence Bragg (con), 1890-

1971, hai nh vt l ngi Anh, giithng Nobel vt l nm 1915)

6. Nhiu x tia X


24/56

24

iu kin nhiu x tia X nh lut BraggCc tia X khng thcsb

phn x m chng b tnx, song rt thun tinnuxem chng l bphnx.

Mi mt phng nguyn tphn x sng ti c lpvi nhau v c coi lmtphnx.

Tia nhiuxccoi l tia

phnx.iukinnhiux: n= 2dsin.l bcsng tia X ti; d l khongcch giacc mtphngtronghmtphngsong song; l gc phnx; n l bcphnx.

6. Nhiu x tia X


25/56

25

Ch nhng h mt phng

song song tha mn nhlut Bragg mi cho chmtia nhiuxc thquan stc.

Mun tha mn l Bragg

phi c 2d, m trongtinh thd c nn chthyhin tng nhiu x tia X(khng thy hin tngnhiuxcanh sng nhn

thyv tia (?))Mtmtphngchphnxmtphnrtnhchm tia X ti,v nukhng th mtphngutin phnxht,skhng cn g ccmtphngsau phnxv nhvyskhng c hintnggiao thoa.

6. Nhiu x tia X


26/56

26

H mt phng phn x c

th l bt k mt h mtphngno ca tinh th,do trong tinh th c rtnhiu h mt phng phnxkhc nhau. (ch khng

nhm ln gia mt phngphnxvimtngoi catinh th)

Bn chtca tia ti c thkhc nhau (tia X, ntron,

electron, ..). Cc tia nycngkhng nhtthitritngoi vo tinh th m cthnmngay trong tinh th.

6. Nhiu x tia X


27/56

27

nh lutBragg ch l hquca tnh tun hon tnh tinca mng tinh th,nn khngphthucvo nntinh th. Snguyn tcanntinh thch

quyt nh cng tngi ca chm tia nhiu x cc bcn khc nhau.

Trong hu ht cc trng hp, bc phn x th nht (n = 1)csdng,v nhlutBragg cvit:

= 2dsin

Khi n > 1, cc phnxcgil phnxbccao.

6. Nhiu x tia X


28/56

28

Nhc li mt s kin thc v mt phng

Bn bao gi t hi, trong h lpphng, h mt phng c ch s Miller(010) v h mt phng c ch s Miller

(020) khc nhau iug cha.... Ddng thyrnghai hmtphng(010)

v (020) song song vi nhau nhng ckhong cch khc nhau. H mt phng(010) c khongcch ngnnhtgiacc

mtphngl d(010)= 1; trong khi hmtphng (020) c khong cch ngn nhtgiacc mtphngl d(020)= .

6. Nhiu x tia X


29/56

29

Mtcch tngqut, cc mtphng(hkl) v (nh nk nl), vinnguyn, l song song vinhau nhngkhongcch giaccmt(nh nk nl) bng1/n khongcch giacc mt(hkl)

d(nh nk nl)= d(hkl)/n

Tby gi tri, ta k hiu(HKL) thay cho (nh nk nl). Nhvy,cc chsh, k, l khng c cschung, nhngH, K, Lth lic.

V d,trong tinh thMgO, khongcch giacc mt(200) l

0,2106 nm, khongcch giacc mt(400) l 0,1053 nm.

Nhc li mt s kin thc v mt phng

6. Nhiu x tia X


30/56

30

Tr li vi iu kin nhiu x Bragg Ta c: n= 2d(hkl).sin

Khi n = 1: = 2d(hkl).sin

Khi n>1, ta c thvitli:

= 2(d(hkl)/n).sin= 2d(HKL).sin

Nhvy,phnxcahmt(nh nk nl) c thccoi l phnxbcn cahmtphng(hkl) v ngcli.ngintrong cctrnghpta c thvitl:

= 2d(HKL).sin

Trong qu trnh khai thc ginnhiuxtia X, ngita itm ccchs(HKL) thay v tm cc chs(hkl).

6. Nhiu x tia X


31/56

31

Ch :

nhlutBragg chl iukincnsong chacho nhiuxbitinh th. iukinny chhon ton ngivicc mngchc cc nguyn tnh. ivicc mngcnc cc nguyn tnmtivtr khc (tm mt,tm khi) s

c hintngmtimtstia nhiux.i vi mng lptk: ch c cc

mt (HKL) vi tngH+K+L lmt s chn th mi cho tia

nhiuxivi mng lptm: ch c cc

mt(HKL) viH, K, Lphi lchnchoclcth micho tia nhiux.

6. Nhiu x tia X


32/56

32

Ttccc tia nhiuxquan st cutun theo iukinBragg nhngc nhngphnxtun theo iukinBragg likhng thquan st c(tcl c cngbng0).

giithch iuny, ta coi tia nhiuxl tphpcc tia tnxgy ra bicc imchkhng phil cc tia phnxgy

ra bicc mtna. Ta cnphixt lnlt:

- Stn xbicc electron trong mtnguyn t.

- Stn xbimtnguyn tclp.

- Stn xbicc nguyn ttrong mt nv.

7. Cng tia X nhiu x


33/56

33

Tn x bi mt electron

J.J. Thomson chngminh crng: cngtia X tn xbimtelectron tikhongcch r ktelectron c intch ev khilngM ccho bicng thc:

2sincMr

e

.II2

422

4

o

Iocng tia x ti

ctc nh sng trong chn khng2- hng tn x

Io I

e2

7. Cng tia X nhiu x


34/56

34

Tn x bi mt nguyn t

Cngtia X tn xbihtnhn l rtnh,bqua.

Sng tn x ton phncanguyn tbng tngcc sng tn xcacc electron trong nguyn t. Do cc sng thnh phnccc pha khc nhau nn cngtn xtngcngkhng nginl bi s ca cng sng thnh phn m l ph thuc vohngtn x.

Tsf theo cng thcdiycgil thastn xnguynt:

bin sng tn xbimtnguyn tf =bin sng tn xbimtelectron

7. Cng tia X nhiu x


35/56

35

Tn x bi mt nguyn t

0 2 4 6 8 10

10

20

30

fCu

fAl

fO

sinnm-1

Gi trf phthucv v . Khi= 0 th f = Z (tngselectron)nhng f gim khi tng v

gim. thf l mthm ca(sin)/,

i vi Cu, f gim t 29 khi(sin)/tng.

7. Cng tia X nhiu x


36/56

36

Nhiu x bi mng c s

lchpha giahai sng tn xbihai nguyn tB(u,v,w) v

A(0,0,0) iviphnx(hkl) l:

= 2(hu+kv+lw)

Phng trnh sng t A: A= fA.eikx

Phng trnh sng t B: B= fBei(kx+ ) = fB.ei.eikx

Bin ca sng tn x bi cc nguyn t trong mt n v ivi phn x (hkl) bng:

Io

B

(hkl)

I

A

n

j

jjjj lwkvhuif1

)](2.exp[. F(hkl)= f1.exp(i1) + f2.exp(i2) + . =

7. Cng tia X nhiu x


37/56

37

Nhiu x bi mng c s

F cgil thascutrc Cngtia nhiuxtlthunvi|F(hkl)|2.

Cc phnxc F = 0 sc cngbng0 phnxbcm

Phngtrnh ny p dngcho mimngtinh th. Cho php xc

nhnhngphnx(hkl) no mcd thamn iukinBraggnhngkhng quan st c.

n

j

jjjj lwkvhuif1

)](2.exp[. F(hkl)= f1.exp(i1) + f2.exp(i2) + .) =

7. Cng tia X nhiu x


38/56


39/56

39

Tha s cu trc mng lptk

h+k+l l s chn th F = 2f quan st c

h+k+l l s l th F = 0 khng quan st c

Cc phn x quan st c:

(100), (110), (111), (200), (210), (211), (220), (300), (221), (310),

Xt mt csgmmtnguyn tvtr (0,0,0) v mtnguyn t(1/2,1/2,1/2).

Thay vo biuthctnh F:

F = f.[1+ei..(h+k+l)]

7. Cng tia X nhiu x


40/56

40

Tha s cu trc mng lptm

h, k, l cng chn hoc cng l th F = 4f quan st c

h, k, l l hn hp th F = 0 khng quan st c

Cc phn x quan st c:

(100), (110), (111), (200), (210), (211), (220), (300), (221), (310),

Xt bn nguyn t v tr (0,0,0),(1/2,1/2,0), (0,1/2,1/2), (1/2,0,1/2).

Thay vo biu thc tnh F:

F = f.[1+ei..(h+k)

+ ei..(k+l)

+ ei..(h+l)

]

7. Cng tia X nhiu x


41/56

41

Tha s cu trc mng kim cng

Cc phn x khng quan st c:

(100), (110), (111), (200), (210), (211), (220), (300), (221), (310),

Xt tm nguyn t v tr (0,0,0), (0,1/2,1/2),(1/2,0,1/2), (1/2,1/2,0), (1/4,1/4,1/4),(1/4,3/4,3/4), (3/4,1/4,3/4), (3/4,3/4,1/4).


F = f.[1+ ei..(h+k) + ei..(k+l)+ ei..(h+l) + ei..(h+k+l)/2 +

ei..(h+3k+3l)/2+ ei..(3h+3k+l)/2+ ei..(3h+3k+l)/2]

7. Cng tia X nhiu x


42/56

42

Tha s cu trc mng NaCl

h, k, l cng chn th F = 4(fNa+ fCl)

h, k, l cng l th F = 4|fNafCl|

h, k, l l hn hp th F = 0 khng quan st c

Nh vy c s thay i t l cng so vi mng lptm

Xt mt ion Cl- v tr (0,0,0), v mtion Na+(1/2,1/2,1/2)


F = [fCl+ fNa.ei. .(h+k+l)].[1+ei..(h+k) + ei..(k+l)+ ei..(h+l) ]

7. Cng tia X nhiu x


43/56

43

Bng quy tc lc la cho mt s cu trc tinh th

Loi tinh th Mng Bravais Phn x quan st c Phn x b cm

n gin n gin h, k, l bt k Khng c

Tm khi Tm khi h + k + l chn h + k + l l

Tm mt Tm mt h, k, l cng chn hoc l h, k, l hn hp

NaCl Lptm h, k, l cng chn hoc l h, k, l hn hp

Kim cng Lptm Nhlptm: cng lhoccng chn v h + k + l =4N.

h, k, l hn hp vcng chn nhngh + k + l 4N

Tm y Tm y h v k chn hoc chaicng l

h v k hn hp

Lc phngcht kht

Lc phng h + 2k = 3N vi l chn

h + 2k = 3N + 1 vi l l

h + 2k = 3N vi l l

h + 2k = 3N + 1

vi l chn

7. Cng tia X nhiu x


44/56

44

Nguyn tc

Sdngtia X nsc.

Mudidngbt,kch thcht0,01-0,001mm.

V bt gm v s vi tinh th nh

hng hn lon nn trong mulun c nhngmt (hkl) nmvtr to vi chm tia ti mt gc thamn iukinBragg.

Cc tia nhiuxcacng mth

mtphng(hkl) tothnh mtmtnn vinhl mu,trcl tia ti.

Gc gia tia tiv tia nhiux l2.

8. Phng php bt


45/56

45

Phng php chp phim Debye Scherrer

Thit b: Phim c lt st vothnh trong camthpkim loihnh tr- gil camera. Camerac bn knh xc nh.

Mu c t trn mt gi nm trc trung tm cacamera.

Kt qu: trn phim c nhngcung trn ixngqua vttrung

tm. Yu cu ca phng php l

vchnhiuxphimnh, c enu,nnphim phisng cccc vchyu.

8. Phng php bt


46/56

46

Phim c ra, ct v triphng.

o khong cch tng igia cc vch, tnh gc phn

x, t xc nh c ccc trng ca tinh th nghincu.

Phng php chp phim DebyeScherrer

8. Phng php bt


47/56

47

Xc nh gc

2W

S

1

W

S1

2

2Hoc

8. Phng php bt


48/56

48

Gin nhiu x tia X:

8. Phng php bt


49/56

49

Xc nh cu trc tinh thNhn bit mng Bravais.

Xc nh ch s phn x.

Tnh hng s mng.

8. Phng php bt


50/56

50

Diffraction Angles

sin2

sin2

d

d

rhombohedral

hexagonal orthorhombic

cubic: 2222

22

2

222

2 4sin

1lkh

aa

lkh

d

2

2

2

2222

2

2

2

22

2

43sin

3

41

c

l

a

khkh

c

l

a

khkh

d

322

2222222

322

22222

2

cos2cos31

coscos2sin

4sin

cos2cos31

coscos2sin1

a

hlklhklkh

a

hlklhklkh

d

2

2

2

2

2

222

2

2

2

2

2

2

2

4sin

1

c

l

b

k

a

h

c

l

b

k

a

h

d

Lc phng Trc giao

Lp phng

Hnh thoi

8. Phng php bt


51/56

51

S th t 1 2 3 4 5 6 7 8 9 10

LPG H2+ K2+ L2

HKL1

100

2

110

3

111

4

200

5

210

6

211

8

220

9

300

221

10

310

11

311

LPTK H2+ K2+ L2

HKL2

110

4

200

6

211

8

220

10

310

12

222

14

321

16

400

18

411

330

20

420

LPTM H2+ K2+ L2

HKL

3

111

4

200

8

220

11

311

12

222

16

400

19

331

20

420

24

422

27

333511

KC H2+ K2+ L2

HKL3

111

8

220

11

311

16

400

19

331

24

422

27

333

511

32

440

35

531

40

620

Ch s giao thoa ca 10 cc i u tin ca gin nhiu x tia X

8. Phng php bt


52/56

52

i vi mng lp phng:

Loi mng

LPG 1 : 2 : 3 : 4 : 5 : 6 :8: 9 : 10 : 11

LPTK 1 : 2 : 3 : 4 : 5 : 6 : 7 : 8 : 9 : 10

LPTM 1: 1,33 : 2,66 : 3,67 : 4 : 5,33 : 6,33 : 6,67 : 8 : 9

Kim cng 1: 2,66 : 3,67 : 5,33 : 6,33 : 8 : 9 : 10,67 : 11,67 : 13,33

2

1

2

1

2

1

2

i

2

i

2

i

1

2

i

2

2

LKH

2

LKH

LKH

LKH

sin

sin

d

dQ

iii

111

(?)

8. Phng php bt


53/56

53

- o nhiu x tia X mu nghin cu

- Xc nh cc gc nhiu x (v tr ca cc pic)

- Tnh gi tr Q t

- So snh Q tnh c vi gi tr Q l thuyt (bng trn)- Nhn bit mng Bravais

- a ra kt lun v ch s cc pic

- Tnh cc hng s mng a

- Tnh sai s ca a (a)

f. Xc nh cu trc tinh th

8. Phng php bt


54/56

54

Bng xc nh cu trc

STT 2(o) sin2

Q

H2+ K2+ L2

HKL a aGn ng Chnh xc

12

3

4

56

7

8

8. Phng php bt

8 h h b


55/56

55

V d:

STT 2(O) sin2 QH2+ K2+ L2

HKL a aGn ng Chnh xc

1

23

4

5

13,6

15,822,4

26,2

27,4

0.014019

0.0188910.037727

0.051371

0.056092

1

1.3474812.691036

3.66424

4.001021

3

4.0424428.073109

10.99272

12.00306

3

48

11

12

111

200220

311

222

4,0886

4,06714,0701

4,0900

4,0881

0.0598

0.05110.0359

0.0293

0.0250

1

23

4

56

7 89 10

1112

13

= 0.559

8. Phng php bt

8 Ph h b


56/56

56

Ch :Gi trQ camnglptk v lpgrtgingnhau.quy kttinh thangxt l lptk hay lpgngoi vicnhnbitpic s7 (lpgQ = 8nhnglptk Q = 7), ngita cn davo cngpic. lpg,picthhai trong hai pic uc cnglnhn,cn lptk th pic th

nhtc cnglnhn.Sai s xc nh a trong gn ng bc nht c th tnh theo cngthc:

a = a.cotg.

a ph thucvo nn khng th lytrung bnh cc gi tra nhnc tmipic. Thngngi ta lygi tra ngvipic c gclnnhthoctrung bnh cc gi trngvihai pic cuicng vi>70ohocvtha = f() ringoisuy lncaa n= 90o.

8. Phng php bt

Documents

Chuong 2. Phuong Phap Nhieu Xa Tia X (1)