infrared spectroscopy chapters 16-17 chapter 7- i

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Analytical Chemistry

Infrared SpectroscopyChapters 16-17Chapter 7-IIR Selection RulesChange in dipole moment during vibration

http://www.lsbu.ac.uk/water/vibrat.html

Water Vibrationshttp://chemmac1.usc.edu/Bruno/java/Vibrate.html

Carbon Dioxide Vibrations

FT-IR

Retardation difference in path length of two beams

Interferograms

Infrared SourcesGlowbarNernst glower

Patented sources

DetectorsDLaTGS (pyroelectric)MCT (semiconductor/quantum well)

Thermodetectors (not used for FT-IR, response time is too slow)ThermocoupleBolometerThermister

FT Method AdvantagesFellget Advantage (Multiplex Adv)Collect all at onceFaster, dont need to scan axisJaquinot Advantage (Throughput Adv)No slits or optical elements to limit (attenuate) radiationConnes AdvantageInternally calibrated w/ HeNe laserWavenumber calibration is:More accurateBetter stabilityBlack Body RadiationWhy dont we use a light bulb as IR source? According to Black Body Radiation, it should give more intensity in IR region of spectrum.

ATR / Evanescent wave

Saturated vs. Unsaturated

Saturated vs. Unsaturated

Alcohols

Ketones and Aldehydes

Carboxylic Acids

Ethers

Esters

Unknowns

Unknowns

Unknowns

Unknowns

Unknowns

Unknowns

Raman SpectroscopyChapters 18

Elastic scatteringPhoton scattered at same as incident photon

Inelastic scatteringPhoton scattered at different as incident photon

e- cloud of molecule can be polarized by E.M. radiation

It is possible to induce dipole moment using elect field of E.M.

Size of induced dipole depends on polarizability of e- cloud

Induced dipole momentpolarizabilityOscillating electric fieldRaman Selection Rule with vibration

Polarizability changes with bond length/vibration

Change in bond lengthGaussian CalculationsCO2SF6Chloroform

kTImportant concept in Thermo and Stat Mech

Vibrational Selection RulesRamanInfrared

90 Scattering Instrumentation

Advantages and Disadvantages of RamanAdvantagesWater is weak scatterer

Little sample prep

Sharper peaks than IR

Use of fiber opticsDisadvantagesInsensitive (LOD ~ 0.1%)

Fluorescence interferenceTrade off of / Int / fluor.

Resonance RamanSurface Plasmons electron oscillations at surface of a metal.

Surface Plasmon Resonance when freq of light photons matches the natural freq of oscillating surface electrons.

FT-RamanFiber-Optic Raman SpectrometerBP=band pass filterBR=band rejection filter

Imaging SpectrographHoloPlexTE CooledCCDDetectorSlitNotch ControlElectronicsProbeHeadInvictus NIR LaserKaiser Optical Systems Inc Rxn1 Raman system operating at 785 nmInstrumentation59RNX1: -50 to 3450 cm-1 range. 5 s aq time, 4 accums every 30 s, ~80 mW at sample, 200mW output out of 400 mWPhAT: 0 to 1800 cm-1 range. 1 s aq time, 4 accums every 10 s, ~100 mW at sample, 200mW output out of 400 mW (except small-scale granulations 200 mW at sample with 400 mW output)

Improving Raman Collection EfficiencyCrystal Hydrate Structure

Calibration

- RAT- RMTPhase Transformation upon Water Addition1838.71700160015001400130012001100977.4Raman Shift / cm-1Int immediately3 min6 min9 min12 min15 min18 minApply Calibration to get Kinetic Transformation Profile

Chart35.04479844587.2435021.59976228066.8812763.53316978566.4767323.02762423684.5466796.51042317514.185475.9753361374.706565.9990375044.2818159.97898821294.17872525.6303538694.56917738.66279153574.27000754.45148763364.64365669.98739047434.71151782.47971371244.7885889.79980856954.83690194.70382352684.83711296.28769483025.0699898.97026517524.546963100.43887563175.149505100.95908171144.712538101.69634209524.646626101.86413151764.991227102.08104479824.987761102.10896003834.708924102.24329929494.917358102.35859268775.466143102.12939973114.914053102.51904848424.7640874.5905015.070044.786487

Typical TransformationNo TranformationTime (min)% Hydrate

Sheet10-19.4402427035-14.528204502910.4052167818-2.06149386050-0.315619890210.40521678185.04479844587.2435020.5-18.2793226534-15.11115853446.9254884296-3.52511428080.5-3.72596386856.92548842961.59976228066.8812761-12.7044441184-17.13854315618.2965152969-3.50379166111-1.23017572588.29651529693.53316978566.4767321.5-8.9975659263-13.78994510569.7948931026-2.58789526021.5-3.73964462919.79489310263.02762423684.5466792-20.3874257418-14.464339292211.7740475933-1.848378450321.24679875711.77404759336.51042317514.185472.5-7.8308112261-14.861653802510.4567268028-0.69804255262.51.493945471210.45672680285.9753361374.7065631.342783163-9.46529427712.37225766024.6131673893-0.374182652212.37225766025.9990375044.2818153.530.28077186213.136071270316.040896680216.16393219433.53.917079745716.04089668029.97898821294.178725460.729987917934.434632197630.465029634533.3550132356420.795678103530.465029634525.6303538694.5691774.583.878941723559.964568690846.088880940153.23502830264.531.236702131446.088880940138.66279153574.270007591.37881123580.825034230267.632024122471.825187416541.270951144867.632024122454.45148763364.6436565.593.880332514191.41549787585.025118637285.40241890325.554.949662311485.025118637269.98739047434.711517696.972268820893.8649945393.651844024792.9176206278671.307583400193.651844024782.47971371244.788586.597.757633995.502058599898.046210196.72229984446.581.553407039198.046210189.79980856954.836901798.095472204697.5247733675101.743918444598.5418896295787.6637286091101.743918444594.70382352684.8371127.599.091324106399.024796827199.409580438399.56459016427.593.165809222199.409580438396.28769483025.06998898.724057473998.5888674195101.095604488100.2347863973896.8449258625101.09560448898.97026517524.5469638.598.8356325551101.1660810458102.1237881652100.61199051648.598.7539630982102.1237881652100.43887563175.1495059101.474390628298.9806360575101.7169659222101.36026640979100.4064633948101.7169659222100.95908171144.7125389.5100.7306134968101.8494616984102.324665569101.26667905149.5100.4286441191102.324665569101.69634209524.64662610101.254763598799.7432560259102.9850890353101.460478928610102.3162245305102.9850890353101.86413151764.99122710.5101.1583158605100.7739036967101.0864975461101.0590165510.5102.0436683056101.0864975461102.08104479824.98776111101.448704147100.706336446100.851965975411101.9737445735102.10896003834.70892411.5101.0772432908100.8411262129100.5243926611.5103.331929728102.24329929494.91735812100.0727060397100.0257153211100.783236584712101.4242235831102.35859268775.46614312.5101.4828682203100.906675963912.5102.3196247519102.12939973114.91405313101.2114443504101.347156285413102.6443508582102.51904848424.76408713.513.5102.5931698427102.43289984914.5905011414102.0611788464101.92740554945.0700414.5101.127867959101.59452340274.7864874.6011654.6796394.4678454.45034.1744124.9958415.6089584.5710624.7953254.5944794.9169895.007065.7339015.2369614.9482664.6253615.1257584.4167244.6920364.064784.6820374.4692055.8791694.7682945.7301015.9724884.2846844.5628435.5532864.9077024.6968065.1138534.9410884.9756825.4215515.2690725.0957743.9522174.9667214.5795195.1824984.9912354.8527855.0187155.2627136.1168795.1505655.661184.5438284.4451364.7254224.5944244.3823934.5826124.689074.1442423.883224.6654624.2115313.991454.5542254.6924474.5101794.5365243.8458434.8152213.3464934.4917913.9360494.5124213.7099353.8000433.4104223.3261774.3225774.1095764.4067934.2750113.2601343.5124953.6601572.8963113.9458022.8141973.1183922.6523043.688874

Sheet1

Typical TransformationNo TranformationTime (min)% Hydrate

Sheet2

Sheet3

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