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ĐẠI CƯƠNG CÁC PHƯƠNG PHÁP QUANG PHỔ Lê Nhất Tâm - UIH- IBF [email protected]

Phuong phap AAS

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I CNGCC PHNG PHP QUANG PHL Nht Tm - UIH- [email protected] ni dung chnh:C s ca phng phpBc x in tPhn loi bc x in tTnh cht sng ht ca bc xNng lng vt chtTng tc vt cht vi bc x in tPh hp th- Cc phng php ph hp thPh pht x- cc phng php ph pht x

I CNG CC PHNG PHP QUANG PH I CNG CC PHNG PHP QUANG PHi cng v cc phng php quang phC s ca phng php: Da trn bc x in t c pht ra hay b hp th t mu. Da vo c tnh ca bc x pht ra hay hp th v cng ca chng m ngi ta c th nh tnh hay nh lng thnh phn cc cht c trong mu.BC X IN T+ Bc x in t c bn cht l sng in t. Theo Maxwell th mi bin thin ca in trng u lm pht sinh ra mt t trng v ngc li, mi bin thin ca t trng u lm xut hin mt in trng trong khng gian xung quanh+ Khi mt in tch dao ng vi tn s s lm xut hin mt in trng v mt t trng bin thin cng tn s. Trng tng hp ca in trng v t trng gi l trng in t. Trng in t truyn trong khng gian gi l sng in t

Bn cht ca bc x in tTrong sng in t, in trng E v t trng H lun lun c phng vung gc vi nhau v gc vi phng truyn ca sng in t ( ti mi im cng in trng v cng t trng tng ri gim i chiu

BC X IN T

BC X IN TTrong ph sng in t c mt vng hp t 390nm < < 770nm c th thu nhn c bng mt gi l bc x kh kin.Min kh kin chia lm 7 vng hp vi mu sc khc nhau. Nu i t vng bc sng di ti vng bc sng ngn ta c cc min: , cam, vng, lc, lam, chm, tmPHN LOI BC X IN T

Ni tip vi min tm v pha bc sng ngn l vng t ngoi (UV). Tia v tia rngen (X) l nhng bc x in t c bc sng ngn.Ni tip vi vi min vng bc sng di l min bc x hng ngoi( IR) , tip theo l min vi sng v sng radio ( i truyn thanh)

MT S QUAN NIM V BC X IN TTNH CHT SNG HT CA NH SNGTnh cht sng: Th hin trong vng bc x in t c tn s nh, bc sng ln.

Chemistry 140 Fall 20029The second thing that the wave model of light did not explain was the photoelectric effect

Photoelectric effect occurs when light strikes a metal surface electrons are ejectedIf a potential is applied, then a current flowsThis effect is utilized in automatic door openers, elevator doors, street lights, etc.

It was known that electrons are ejected from a metal only if the frequency is high enough (equal to or greater than the THRESHOLD FREQUENCY.Ex: no electrons are emitted from Cs until the frequency of light reaches 4.6 x 10^14 Hz or greater. Light below this frequency has no effect.Wavelength = Threshold frequency of Cs: c/nu = 3 E 08/4.6 E 14 = 6.52 E -07 meters = 652 nm (Visible orange-red)

Furthermore, the energy of the electron ejected was NOT proportional to the intensity of light (as classical theory had said)The NUMBER of electrons ejected, however, was found to be proportional to the intensity of the light (increased current).

TNH CHT SNG HT CA NH SNG

Tnh cht ht: Th hin trong vng bc x in t c tn s ln, bc sng nh.Chemistry 140 Fall 200210The second thing that the wave model of light did not explain was the photoelectric effect

Photoelectric effect occurs when light strikes a metal surface electrons are ejectedIf a potential is applied, then a current flowsThis effect is utilized in automatic door openers, elevator doors, street lights, etc.

It was known that electrons are ejected from a metal only if the frequency is high enough (equal to or greater than the THRESHOLD FREQUENCY.Ex: no electrons are emitted from Cs until the frequency of light reaches 4.6 x 10^14 Hz or greater. Light below this frequency has no effect.Wavelength = Threshold frequency of Cs: c/nu = 3 E 08/4.6 E 14 = 6.52 E -07 meters = 652 nm (Visible orange-red)

Furthermore, the energy of the electron ejected was NOT proportional to the intensity of light (as classical theory had said)The NUMBER of electrons ejected, however, was found to be proportional to the intensity of the light (increased current).

NNG LNG CA VT CHTNng lng phn t hay nguyn t l tng cc dng nng lng E = Et+Ed+ Eq+ Et = Nng lng in t ca phn t + Ed = Nng lng do nhng dao ng gy bi tng tc gia cc nguyn t trong phn t .+ Eq = Nng lng do s quay ca cc phn t chung quay trong trc no ca n. TNG TC GIA CC BC X V VT CHTKhi chiu bc x in t vo dung dch cha cc phn t th bc x in t c th b khuych tn hoc b hp thu.Ph phn t chnh l ghi li s hp thu bc x bi phn t.Khi phn t hp thu bc x, chuyn t trng thi c bn ln trng kch thch, ngha l bn thn n thay i mc nng lng: E = Ekt Ecb = Et +Ed+ Eq V : Eel > Ed> Eq

TNG TC GIA CC BC X V VT CHT

QU TRNH CHUYN MC S HP THU BC X CA VT CHTPH HP THUKhi nng lng kch thch t gi tr 0,03- 0,3 Kcal/mol, trng thi quay ca phn t bt u b kch thch nhng trng thi dao ng v trng thi in t vn khng i. Lc ny ta ph quay c bc sng di nh hng ngoi xa

Khi nng lng chuyn ng nhit tng ln 0,3- 12Kcal/mol, trng thi in t ca phn t cng cha b kch thch nhng trng thi dao ng bt u b kch thch. Nhng photon tng ng vi bin thin nng lng dao ng c bc sng vo c: = 2500nm- 0,1mm ng vi bc x vng hng ngoi.Lc ny ta c ph thu c l ph dao ng

S HP THU BC X CA VT CHTPH HP THUKhi kch thch cc in t vi nng lng cao hn, vo khong vi chc n vi trm Kcal/mol, th lc trng thi in t bt u b kch thch. Bc x lc ng vi vng kh kin v t ngoi.

Khi bc x b hp thu lm nh hng trng thi in t ca phn t ph thu c c tn s

S HP THU BC X CA VT CHTPH HP THUPH HP THUng biu din s gim nng lng bc x theo i lng c trng ca bc x ( nh di sng, tn s hay s sng) khi bc x chiu qua mu gi l ph hp thu.Vt hp thu dng nguyn t hay phn t ta c ph hp thu nguyn t hay phn t tng ng Tn s bc x b hp thu c ngha c trng c cu trc vt cht . Nghin cu tn s hp thu trn ph nhn din hay nh tnh mu. Da vo ph hp thu c th nh lng mu.

PH HP THUCC LOI PH HP THPh hp th phn t: + Ph hp thu UV-VIS + Ph hp thu IR Ph hp th nguyn t (AAS)

Absorption spectroscopy nh ngha : quang ph hp thu l phng php nghin cu v s hp thu bc x. Bc x b hp thu c xc nh thng qua tn s hay bc sng ca bc x khi bc x tng tc vi mu S thay i cng ca qu trnh hp thu to nn ph hp thu. Ph hp thu c trnh by di dng ph in t

CC LOI PH HP TH21 U.V- Vis Spectrophotometry L ph hp thu trong tt c cc phn t hp th bc sng tng ng vi trong vng UV- Vis. Trong thc phm phng php ny dng nh tnh hay nh lng cc cht c lin quan ti lin kt C-N hay C=O v.v.. Nh nh lng hm lng proteinCC LOI PH HP TH

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CC LOI PH HP TH

Ph IR: L ph hp thu trong tt c cc phn t hp th bc sng nh sng tng ng vi trong vng IR. Quang ph hng ngoi cung cp kh nng o cc loi dao ng khc nhau ca cc lin kt gia cc nguyn t cc tn s khc nhau.CC LOI PH HP TH

Ph nghin cu s hp thu trong vng t 1- 2,5m, 2,5-25m, ngoi 25m Ph hng ngoi thu c ca Polystyren trong vng mid IRCC LOI PH HP THAtomic absorption spectroscopy nh ngha : ph hp thu nguyn t l k thut dng xc nh hm lng ca cc kim loi c trong mu th K Thut ny c th dng phn tch hm lng trn 70 nguyn t kim loi khc nhau c trong dung dch

Atomic Absorption Spectrometer CC LOI PH HP TH26Cc qu trnh xy ra khi nguyn t ha bng ngn la27

Dung dchPhun sngSngLoi dung miSol kh kh

Bay hiNguyn t t doDng phn tDng ionCC LOI PH HP TH27S PHT X CA VT CHTVt cht dng nguyn t hay phn t, nhn nng lng bc x thch hp, chuyn mc nng lng thp (bn) ln mc nng lng cao hn (km bn), c khuynh hng tr li mc nng lng thp hn v c th pht ra bc x, l hin tng pht x.

S PHT X CA VT CHT

S PHT X CA VT CHT

S PHT X CA VT CHTCC LOI PH PHT XPh pht x nguyn t (AES)Ph hunh quangPh pht x ion (ICP) Atomic emission spectroscopy

nh ngha : l mt phng php nh lng da trn vic o cng bc x pht ra t cc nguyn t khi chng chuyn t trng thi kch thch v trng thi c bn. T ngi ta xc nh hm lng cht xc nh.

CC LOI PH PHT X33Ph hunh quangnh ngha : trong phng php ny lng cht c trong mu c th c xc nh bi lng bc x pht ra bi cc nguyn t cu to nn mu.. Phng hp ny da trn hin tng hunh quang fluoroscence.

CC LOI PH PHT X34

Cc qu trnh xy ra trong ICPCC LOI PH PHT X