Instrumental Analysis - Lecture 10 PDF

Preview

Summary

Instrumental Analysis - Lecture 10...

Description

CHEM 3420/7420G 3420/7420G"" ! Instrumental Analysis Pro Proff. Br ian Gibney! 2411 N New ew Ing Inge er soll soll!! bg bgibn ibn ibney@ ey@ ey@bro bro brook ok okllyn. yn.cuny cuny cuny..edu du!!

Course Business! Thur Thursday sday sday!! !Ex Exam am II!! ! 6: 6:30 30 – 8: 8:30 30 pm ! ! Br Brin in ing g nno on-pr n-prog og ogrram ammabl mabl mable e ccal al alcu cu cullator! ! See e ex xampl ample e oon n websi websitte! !No L Lab ab e exper xper xperimen imen iments ts ts!! Tu Tue esday! pH Poten entio tio tiom metr try y llab ab due due!!

1!

Chapter 6: Spectrometry ! El Ele ectr tro omag magn netic Ra Radi di dia atio tion n! !- ene energy rgy rra a di dia ate d in the ffor or orm m of a ! wave ccau au ause se sed db by y the in intterac actio tio tion n of ! an el elec ec ectr tr triic an and d magn magne etic field field!! !- a sstr of quan iz d ene tr tream eam quantt ize e energy rgy ! ! pa ts, or pho pac ckets, phottons ons!! !- doe n t r doess no o requir equir equire e a me mediu diu dium, m, can ! ! tr travel avel thr thro oug ugh h vva acuu cuum m! ! !!!!

Chapter 6: Spectrometry ! El Ele ectr tro omag magn netic Ra Radi di dia atio tion n (pl (plan an ane ep pol ol olariz ariz arize ed) d)!!

2!

Chapter 6: Spectrometry ! El Ele ectr tro omag magn netic Ra Radi di dia atio tion n! !- wavel wavelen en ength gth (λ) dis disttance ! ! !!from from oone ne maxima tto o next next,, nm, Å Å!! !- pe perr io iod d (p (p)) tim time e ffor or oon ne wavel wavelen en ength gth tto o pa pass ss ss!! !- fr ( ν = 1 p ) w o n d ! frequency equency 1/ / wavel avel avelengths/ engths/ engths/se se sec c !- vel ci of p o p oga (m/ ) ! velo o city ty prr ogatio tio tion n (m/ss ! !v i = ν λi! ! maximu maximum m is spee speed d of llig ig igh ht,! ! !!llatin “cel “cele er itas” = c = ν λi! !- wavenu wavenumber mber mberss (1 (1/ /λ) cm-1#

Chapter 6: Spectrometry ! Ene Energy rgy of el elec ec ectromag tromag tromagn netic rra adia diatio tio tion n! !E = h hν ν! !Pl Planck’ anck’s ccons ons onsttan antt (h (h)) = 6.626 x 10-34 J•s J•s!! !E = hc/ hc/λ λ = hc (1 (1/ / λ) ! Ene Energy rgy is inve inversel rsel rsely yp prropo portio rtio rtional nal tto o wavel wavelen en ength gth gth!! ! !!!! Ene Energy rgy is dir direc ec ectl tl tly y pr pro opo portio rtio rtiona na nall tto o waven wavenu umbe mberr s#

3!

Chapter 6: Spectrometry ! Re Refr fr fra active In Inde de dex x of a Ma Matter ial al!! !- the spee speed d of llig ig igh ht dep depen en ends ds on tthe he m me e diu dium m! !- the fr freq. eq. an and d ampl ampliitu tude de do nno ot! !- the wavel wavelen en ength gth dep depen en ends ds oon n the m me e diu dium m! !- rra atio of sp spee ee eed d of llig ig igh ht in a m me ediu dium m tto o ! ! spee of l t in a v cuu is the speed d lig ig igh h va acuum m the!! ! ! rre efr fra active in inde de dex x of the ma matter ial !

Chapter 6: Spectrometry ! Re Refr fr fra active In Inde de dex x of a Ma Matter ial al##

4!

Chapter 6: Spectrometry ! El Ele ectr tro omag magn netic Spec Spectr tr tru um#

Chapter 6: Spectrometry ! Spe Spec ctr tro ometr triic Me Metho tho thods ds ds##

5!

Chapter 6: Spectrometry ! Wave p prrope pert rt rtie ie iess of el elec ec ectromag tromag tromagn netic rra a di dia atio tion n! ffor or a sin singl gl gle e wave wave,, y = A sin (2 (2πν πν πνtt + φ)! !A = ampl ampliitu tude de de!! !φ = phase an angl gl gle e! for mu tipl for mulltipl ple ew waves aves aves,, ! !y = A1 sin (2 (2πν πν1t + φ1) + A2 sin (2 (2πν πν2t + φ2) …!

Chapter 6: Spectrometry ! Ef Efffect of phase sh shiift! - sol solii d lline ine is su sum m of (1) an and d (2) (2)!! - ((a) 20° phase sh f t ; (b 20 a) shii (b)) 200° 0° phase sh shiift!

6!

Chapter 6: Spectrometry ! Using sin sine e wave wavess tto o mak make e! a squar square e wave wave!! vs

!3 sine wave wavess! !9 sine wave wavess!

Chapter 6: Spectrometry ! Di Difffr fra actio tion n! !waves pr pro opaga pagatte! !throug a through h sl sliit! !sl sliit w wiidth > λ! vs vs..!

!sl sliit w wiidth = λ!

7!

Chapter 6: Spectrometry ! Di Difffr fra actio tion n! !singl single e sl sliit + +!! !do doubl ubl uble e sl sliit! !cons onstr tr truc uc uctive tive tive!! !de desstr truc uc uctive tive ! !in intterferenc rference e!

Chapter 6: Spectrometry ! Di Difffr fra actio tion n Geo Geome me metr tr try y! !λ = CF = BC sin sinθ θ! !nλ = CF = BC sin sinθ θ! !DE = OD sin sinθ θ#

8!

Chapter 6: Spectrometry ! Di Difffr fra actio tion n Geo Geome me metr tr try y! !nλ = (BC DE)/ DE)/OE OE OE!! !OE is dis disttance fr fro om ! ! scr screen een tto o pl plan an ane e of ! ! sl sliits ts!! !BC is sl sliit spa spacing cing cing!! !DE is b ban an and d spa spacin cin cing g!

Chapter 6: Spectrometry ! Supp Suppose ose the screen is 2.0 2.00 0 m from tthe he pl plan an ane e of the sl sliits w wiith a sl sliit spa spacing cing of 0. 0.300 300 m mm m. Wha Whatt is the wavel of the 4th b i i is 15. wavelen en ength gth ban an and d iff itt 15.3 3m mm m from the cen ba d? ! centr tr tral al ban n !nλ #4λ ! !λ

= (BC DE)/ DE)/OE OE OE!! = (0 (0..30 300m 0m 0mm m) (15. (15.3m 3m 3mm m)! !!/ /200 2000m 0m 0mm m! = 57 578 8 nm nm!!

9!

Chapter 6: Spectrometry ! Fo ur FFa ates of the Pho Phottons ns!! !!!!-

tr transm ansm ansmissio issio ission n! rreflec eflec eflectio tio tion n! sc sca atter ing ing!! abso absorr ptio ion n!

Chapter 6: Spectrometry ! Tra Tran nsm issio n! !- vel velo oci city ty of llig ig igh ht ffas as asttest in vva acuu cuum m! !! !

el tric field in ele ectri intterac acts ts w wiith ma matter ial al!! bu butt pho phottons nno ot abso absorbe rbe rbed d an and d there is ! nno o pe perr man manen en entt en ene ergy tr transf ansf ansfe e r!

!- sl slo ow ing due tto o rre efr fra active in inde de dex x of ! ma matter ia iall (ni)! ! ni = c/ vi!

!

10!

Chapter 6: Spectrometry ! Reflec Reflectio tio tion n! !- llig ig igh ht is al always ways reflec reflectte d w when hen iitt pa passe sse ssess ! from a ma matter ial of oone ne re refr fr frac ac active tive in inde de dex x ((n n) ! tto o an ano other ther!! !- g grea rea reattest for llar ar arge ge chan chang g es in n! !Ir/Io = ((n n2 - n1)/( )/(n n 2 + n 1) ! !Ir = rreflec eflec eflectte d in inttensi ensity ty ty!! !I0 = inpu inputt in inttensi ensitty!

Chapter 6: Spectrometry !

Sc Sca att tte erin ing g! !- Rayl Rayleig eig eigh h sc sca atte rin ring g! ! !!-- parti particl cl cle es small smalle er than λ! ! !!-- p prroport ortio io ional nal tto o λ-4! ! !!-- p prroport ortio io ional nal tto o (parti (particl cl cle e siz size e)2! ! !!-- P Pol ol olym ym yme er M MW W de detter mina minatio tio tions ns ns!! !- Raman sc sca atter in ing g (l (lo ow in inttensi ensity) ty) ty)!! ! !!-- sc sca attere d rra a di dia atio tion n di diff ff ffe eren rentt ! ! ! from inpu inputt rra a di dia atio ion nb by y mol mole ecu cullar ! ! ! vibr vibra atio tion n! ! !!E E=h hν νex -/+ ΔE! ! !!w whe herre ΔE = vibr vibra atio tiona na nall ene energy rgy! ! !!-- vibr vibra atio tional nal sp spec ec ectr tr trosc osc osco opy py!!

11!

Chapter 6: Spectrometry ! Ab Abssor pt ion! !- ma matter ia iall abso absorbs rbs pho photton! !- ne nett ene energy rgy tr transf ansf ansfe er tto o ma matter ial ! A = -l -lo og T = llog og P0/P! !A = abso absorbanc rbanc rbance e! !T = tr transm ansm ansmiittanc ance e! !P0= Inpu Inputt Powe Powerr! !P = P Po owe werr a affter sampl sample e!

Chapter 6: Spectrometry ! Bee Beer’ r’s Law Law!! A = εbc! bc! !A = abso absorbanc rbanc rbance e! !ε = mol molar ar abso absorr ptivi tivity ty (M-1cm-1)! !b= sampl sample e pa pathl thl thlen en ength gth ((cm cm cm))! !c = cconcen oncen oncentr tr tra atio ion n of sampl sample e (M (Mol ol olar ar ar))! Ene Energy rgy dissi dissipa pa patte d as mol mole ecu cullar vibr vibra atio tions ns (hea (heatt) or a ass an em emiitte d pho photton (l (lu umine inesscenc ence e)!

12!

Chapter 6: Spectrometry ! Bee Beer’ r’s Law Law!! !- Abso bsorb rb rbanc anc ance e is a ad ddi ditive tive tive!! A = ε1bc1 + ε2bc2 + ε3bc3 + …! Abso bsorb rb rbanc anc ance ea att any wavel wavelengt engt ength h is the su sum m of the abso absorb rb rbanc anc ance e of ea eac ch in indivi divi dividual dual cco o mpo mpon nen entt of the sampl sample e! Ea Each ch cco omp mpo onen entt has iits ts oow wn mol molar ar abso absorr ptivi ivity ty an and d cco oncen ncentr tr tra atio ion n, al alll hav have e sam same e pa pathl thl thlength ength ength!!

Chapter 6: Spectrometry ! Ab Abssor pt ion Sp ect ctro ro rosco sco scop py ! - At Ato o mic Abso bsorr ptio tion n Spec Spectrosc trosc trosco o py ( AAS AAS))! -M tio n Spec Mol ol olecu ecu ecullar Abso bsorr ption Spectrosc trosc trosco o py ! !- El Ele ectr tro onic ((UV UV UV--vis vis))! !- Vibr Vibra atio ional nal (IR (IR,, Raman Raman))! !- Ro Rottatio tional nal (Mi (Micr cr cro owave wave)) ! - Magn Magne etic Spec Spectrosc trosc trosco opy py!! !- Nucl Nuclea ea earr spin (NMR) (NMR)!! !- El Ele ectr tro on spin (ESR (ESR/ /EPR) EPR)!!

13!...