Infrared spectroscopy book pdf

Chemical Analysis of Polymeric Materials Using Infrared Spectroscopy and infrared spectroscopy data
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Published Date:12-07-2017
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Chemical Analysis of Polymeric Materials Using Infrared Spectroscopy Charles Yang Department of Textiles The University of Georgia Athens, Athens, GA 30602, USA University of Zagreb, Croatia, November 3, 2011‡‡‡ Outlines Basic Theory of Infrared Specrtrocopy Molecular vibrational energy, infrared spectroscopy and its selection rules Interpretation of Infrared spectra, group frequency and finger print region Dispersive versus Fourier transform infrared spectroscopy The sampling techniques for solids Applications of FT-IR spectroscopy to polymers: qualitative analysis Applications of FT-IR spectroscopy to polymer: quantitative analysisM M 1 2Vibrational Energy of A Diatomic Molecule V - vibrational quantum number, 0, 1, 2… H - Plank constant V - vibrational frequency m µ- reduced mass M M 1 2 M M 12 k- force constant-1 Wavenumber (cm ) of An IR Absortion Peak 5 a. Force constant-10 dynes/cm -24 b. Reduced mass - 1.673 x 10 gAn Absorption Peak in An Vibrational Spectrum CO (gas)An Absorption Peak with Rotational Fine Structure in An Vibrational Spectrum CO (gas)Electric Magnetic RadiationNear-, Mid-, and Far-Infrared Region‡‡ Selection Rules of Infrared Spectroscopy Excitations from V=0 (ground state) to V=1 st (1 excited state (fundamentals) by absorption of IR radiation Absorption can occur only when there is a change in the magnitude and direction of dipole moment of the bondVibrational Modes‡‡‡ Infrared Spectra Interpretation: Group Frequency Start in the group frequency region: -1 4000-1250 cm (-OH, -NH, =C-H, -CH , 2 -CH , CH-, P-H, C=O…) 3 Easy to interpret, little interference Peak assignment Peak position (wavenumbers) Peak height Peak shape ‡‡‡‡ Infrared Spectra Interpretation: Finger Print Region More complex and more difficult to interpret Small structural differences results in significant in spectral differences Complete interpretation impossible Complete identification requires 100% match between sample’s and standard’s spectra in the finger print regionInfrared Spectroscopy: Group Frequency raRed/infrared.htmStretching Vibrations Bending Vibrations -1 -1 Functional Class Range (cm ) Intensity Assignment Range (cm ) Intensity Assignment Alkanes 2850-3000 str CH , CH & CH 1350-1470 med CH & CH 3 2 2 3 2 or 3 bands 1370-1390 med deformation 720-725 wk CH deformation 3 CH rocking 2 Alkenes 3020-3100 med =C-H & =CH (usually sharp) 880-995 str =C-H & =CH 2 2 1630-1680 var C=C (symmetry reduces 780-850 med (out-of-plane intensity) 675-730 med bending) 1900-2000 str cis-RCH=CHR C=C asymmetric stretch Alkynes 3300 str C-H (usually sharp) 600-700 str C-H deformation 2100-2250 var C≡C (symmetry reduces intensity) Arenes 3030 var C-H (may be several bands) 690-900 str-med C-H bending & 1600 & med-wk C=C (in ring) (2 bands) ring puckering 1500 (3 if conjugated)O-H (free), usually 1330- O-H bending (in- 3580-3650 var sharp med Alcohols & 1430 plane) 3200-3550 str O-H (H-bonded), var- 650- O-H bend (out-of- Phenols 970-1250 str usually broad wk 770 plane) C-O 3400-3500 (dil. soln.) wk N-H (1°-amines), 2 1550- med NH scissoring (1°- Amines 2 3300-3400 (dil. soln.) wk bands 1650 -str amines) 1000-1250 med N-H (2°-amines) 660- var NH & N-H 2 C-N 900 wagging (shifts on H- bonding) 2690-2840(2 med C-H (aldehyde C-H) Aldehydes & bands) str C=O (saturated 1350- strα-CH bending 3 Ketones 1720-1740 str aldehyde) 1360 strα-CH bending 2 1710-1720 C=O (saturated 1400- med C-C-C bending str ketone) 1450 1690 str 1100 1675 str aryl ketone 1745 strα, β-unsaturation 1780 cyclopentanone cyclobutanone 2500-3300 (acids) str O-H (very broad) 1395- med C-O-H bending Carboxylic Acids overlap C-H str C=O (H-bonded) 1440 & Derivatives 1705-1720 (acids) med O-C (sometimes 2- 1210-1320 (acids) -str peaks) 1785-1815 ( acyl str C=O halides) str C=O (2-bands) 1750 & 1820 str O-C (anhydrides) str C=O med N-H (1°-amide) II 1040-1100 str O-C (2-bands) 1590- med band 1735-1750 (esters) str C=O (amide I band) 1650 N-H (2°-amide) II 1000-1300 1500- band 1630-1695(amides) 1560 dbksupport/irtutor/tutorial.htmlPresentation of Infrared Spectra T% = I /I A = -Log T% t 0 10‡‡‡‡‡ Instrumentation of Infrared Spectrometer Source Monochromator (dispersive IR spectrometer) or Interferometer (FT-IR spectrometer) Sample device Detector Data processing, presentation and storage device

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