Infrared and Raman Spectroscopy

Transcription

1 Infrared and Raman Spectroscopy Methods and Applications Edited by Bernhard Schrader Contributors: D. Bougeard, M. Buback, A. Cao, K. Gerwert, H. M. Heise, G. G. Hoffmann, B. Jordanov, W Kiefer, E.-H. Körte, H. Kuzmany, A. Leipertz, E. Lentz, J. Liquier, A. Röseler, H. Schnöckel, B. Schrader, H. W Schrötter, M. Spiekermann, E. Taillandier, H. Willner VCH Weinheim New York Basel Cambridge Tokyo

2 Early history of vibrational spectroscopy (B. Schröder) 1 2 General survey of vibrational spectroscopy (B. Schröder) Molecular vibrations Methods of observing molecular vibrations The infrared spectrum The Raman spectrum Frequencies of the vibrations of typical model molecules Stretching vibrations of linear triatomic molecules Stretching vibrations of cyclic molecules and molecular chains General rules concerning vibrations Estimating force constants Vibrational spectra of molecules in different states The symmetry of molecules and molecular vibrations Symmetry Operators, symmetry elements Point groups, space groups Selection rules of the vibrations of molecules and crystals Definition of a group, multiplication tables Representations of a group Irreducible representations The character table The number of vibrational states belonging to the different symmetry species 50

3 VIII Table of Contents The number of vibrational states of a molecular crystal 51 Vibrational spectra of thiourea molecules and crystal modifications 54 Vibrational states of the free thiourea molecule 54 Vibrational states of the thiourea molecule under the constraints of its site symmetry 56 Vibrational states of the unit cell of crystalline thiourea 56 Correlation of the motional degrees of freedom of thiourea 57 Infrared and Raman activity of lattice vibrations 61 3 Tools for infrared and Raman spectroscopy (B. Schröder) The optical conductance The optical conductance of spectrometers Properties of grating spectrometers Properties of prism spectrometers Optical conductance of prism and grating spectrometers Optical conductance of interferometers Application of dispersive spectrometers and interferometers to vibrational spectroscopy; the Jacquinot advantage Interference filters Lasers Polarized radiation (B. Jordanov) The Stokes - Mueller formalism The Stokes vector The Mueller matrices Polarization optics Linear polarizers Retarders Properties of the components of optical spectrometers (B. Schröder) Radiation sources Imaging and conducting optical elements Radiation detectors, signal-to-noise ratio Optimizing vibrational spectroscopy as an analytical method Basic information theory Information theory applied to analytical chemistry The precision of spectrometric analysis and the limit of detection Multichannel and multiplex techniques, the Fellgett advantage 120

4 IX 3.4 Spectrometers for the near, middle, and far infrared ränge Radiation sources Spectral apparatus Detectors Sample arrangements Radiation balance of an IR spectrometer Raman spectrometers Radiation sources Spectral apparatus Sample techniques Theory Sample arrangements for Raman spectroscopy Micro and 2D scanning arrangements The radiant power of Raman lines Radiation balance of a Raman scattering sample, considering absorption by the sample or the solvent Special features of Raman spectroscopy in the NIR ränge Influence of the characteristics of sample and spectrometer Conclusions concerning optimization of NIR Raman spectroscopy Nonlinear Raman spectroscopy (W. Kiefer) Nonlinear Raman processes Spontaneous scattering: hyper Raman effect Stimulated Raman effect Nonlinear Raman spectroscopies based on third-order susceptibilities Instrumentation for nonlinear Raman spectroscopy Hyper Raman spectroscopy Coherent anti-stokes Raman spectroscopy (CARS) Scanning pulsed CARS Multiplex CARS Femtosecond time-resolved CARS High resolution cw-cars Special laser beam arrangements for CARS Stimulated Raman gain and inverse Raman spectroscopy (SRGS, IRS) Photoacoustic Raman spectroscopy (PARS) Ionization detected stimulated Raman spectroscopy (IDSRS) 186

5 X Table of Contents 4 Vibrational spectroscopy of different classes and states of Compounds Organic substances (B. Schröder) Chain molecules, polymers General features Special properties of the spectra of polymers C=C vibrations Conjugated and cumulated C=C Systems X=Y=Z derivatives Acetylene derivatives Nitriles Saturated isocycles Dependence of the C-halogen vibrations on the Constitution, the configuration, and the conformation The Substitution pattern of benzene derivatives The ether moiety CH 3 -Xgroups The carbonyl group in different environments Azo Compounds, peroxides, disulfides R-SO n -R and R-SH groups Nitro groups Substances of biological interest Solvents Inorganic substances (H. Schnöckel and H. Willner) Introduction Application of vibrational spectroscopy in inorganic chemistry Qualitative and quantitative analysis of known Compounds Qualitative analysis of unknown Compounds. Interpretation of vibrational spectra with the help of empirical rules Characteristic frequencies Vibrational coupling Influence of bonding on vibrational frequencies Discussion of structure and bonding with the help of vibrational spectroscopy Geometry, composition, and symmetry Assignment of vibrational absorptions. Normal coordinates Intensity of vibrational bands Isotopic Substitution Force constants Significance of force constants for chemical bonding. Comparison with other properties of bonds 244

6 Prediction of the vibrational spectra of unknown species Vibrational spectra of crystals from a chemical point of view Selected examples of structural examination by vibrational spectroscopy. classified by Compounds Gaseous Compounds Solutions Solids Molecular solids Isolated groups of ionic Compounds Solid ionic Compounds Conclusion Rotation-vibration spectra of gases (H.M. Heise and H.W. Schrötter) Infrared spectra of gases (H.M. Heise) Introduction Linear molecules Symmetrie top molecules Spherical top molecules Asymmetrie top molecules Raman spectra of gases (H.W. Schrötter) Introduction Selection rules and examples of spectra Diatomic molecules Linear molecules Symmetrie top molecules Spherical top molecules Asymmetrie top molecules Raman scattering cross sections Conclusion Matrix-isolated molecules (H. Schnöckel and H. Willner) Introduction Vibrational spectra of matrix-isolated molecules Basic experimental details Methods of matrix preparation and formation of guest species Molecules in the vapor phase Molecules in the vapor phase formed by chemical reaction Spontaneous chemical reactions in a matrix (Cryochemistry) Photochemical reactions in a matrix 312

7 XII Table of Contents 4.5 Crystals (D. Bougeard) Vibration of an unidimensional diatomic chain Qualitative extension to a three-dimensional lattice Single crystal spectroscopy Infrared spectra Raman spectra An investigated example: calcium carbonate Calcite Aragonite Applications Liquid crystals: orientational order and optical anisotropy (E.-H. Körte) Introduction to liquid crystals Degree of order and optical anisotropy of nematics Evaluation of order and orientation The cholesteric helical structure: analysis and application From nematic anisotropy to cholesteric optical activity Infrared and Raman spectroscopy of biomolecules (A. Cao, J. Liquier, and E. Taillandier) Nucleic acids Experimental methods: IR and classical Raman spectroscopy Solutions Films and fibers Crystals What does the vibrational spectrum of a nucleic acid look like? The three main families of nucleic acid double helix conformations The B» A conformational transition The B > Z conformational transition Hydrogen-deuterium exchange Infrared linear dichroism Crystal studies Triple helices DNA-drug interactions Proteins-pigments IR and classical Raman spectroscopy Band assignment and protein conformation Treatment of data Membrane proteins Recent techniques Resonance Raman spectroscopy Surface enhanced Raman spectroscopy 361

8 XIII Near IR FT Raman spectroscopy The cytochrome c System Nucleoproteins Chromatin Viruses Biomembranes Characteristic wavenumbers and spectral regions usually used for membrane studies Infrared absorption bands Characteristic Raman bands Phospholipid model membranes Phase transitions investigated by vibrational spectroscopy The interdigitated phase Effect of drugs on phospholipid model membranes Interactions with ionophores Effect of polycations on charged lipids Phospholipid bilayers in the presence of cholesterol, membrane proteins, and Peptides Effect of cholesterol Interactions with membrane proteins Interaction with hormones Effect of toxins Glycolipids Conducting polymers, semiconductors, metals, and superconductors (H. Kuzmany) Infrared and Raman spectroscopy of Systems with free carriers and resonance transitions Infrared and Raman spectroscopy of conjugated polymers Infrared and Raman spectroscopy of organic charge-transfer crystals Infrared and Raman spectroscopy of semiconductors Infrared and Raman spectroscopy of metals and superconductors Infrared and Raman spectroscopy of fullerenes Summary and conclusion Evaluation procedures Quantitative analysis, automatic quality control (M. Spiekermann) General Relation between measured quantities and concentration Quantitative analysis by IR spectroscopy Calibration methods based on band maxima 416

9 Calibration methods based on integrated intensities Quantitative analysis based on derivative spectroscopy Single component analysis Multicomponent analysis Analysis of binary mixtures without external calibration Quantitative reflection spectroscopy Quantitative analysis by Raman spectroscopy Examples Quantitative analysis of liquid Solutions Gases Solids Quality control Chemometrics 444 Table of Contents 5.2 Calculation of frequencies and intensities of vibrations of molecules and crystals (D. Bougeard) General formulation Internal coordinates Symmetry coordinates Summary of the coordinate Systems Program packages for normal coordinate treatment Potential energy functions Physical significance of force constants Valence stretching Interaction force constants Vibrational frequencies of crystals General treatment Potential function Van der Waals interactions Hydrogen bond Electrostatic interaction Concluding remarks on solid State calculations Vibrational intensities Classical methods Electro-optical theory Polar tensors Quantum chemical methods 462

10 XV 6 Special techniques and applications Applications of non-classical Raman spectroscopy: resonance Raman, surface enhanced Raman, and nonlinear coherent Raman spectroscopy (W. Kiefer) Introduction (yvith M. Spiekermann) Resonance Raman spectroscopy (RRS) Resonance Raman theories The sum-over-states picture (yvith M. Spiekermann) The time-dependent picture Applications of resonance Raman spectroscopy (yvith M. Spiekermann) Anharmonicity constants from overtone progressions Accurate determination of excited State repulsive potential functions of diatomic molecules in the gaseous phase Determination of excited State structure of polyatomic molecules Resonance Raman spectroscopy of biochemical and biological Systems Various applications of resonance Raman spectroscopy Surface enhanced Raman scattering (SERS) SERS theories Techniques for SERS Some applications of SERS Applications of nonlinear Raman spectroscopy Hyper Raman spectroscopy Coherent anti-stokes Raman spectroscopy (CARS) Spectroscopy of gas-phase molecules (yvith A. Leipertz) Femtosecond time-resolved studies in liquids and Solutions Resonance CARS of the solid State Stimulated Raman gain and inverse Raman spectroscopy (SRGS, IRS) Photoacoustic Raman spectroscopy (PARS) lonization detected stimulated Raman spectroscopy (IDSRS) Principles and application of near-infrared spectroscopy (M. Buback) Introduction Near-infrared spectra of small molecules Near-infrared spectra of selected organic Compounds Quantitative analysis via near-infrared spectroscopy Concluding remarks Vibrational optical activity (VOA) (G. G. Hoffmann) Vibrational circular dichroism (VCD) Introduction Instrumental techniques 544

11 XVI Table of Contents Theoretical modeis The degenerate coupled oscillator (DCO) model The fixed partial Charge (FPC) model The Charge flow (CF) model The localized molecular orbital (LMO) model The dynamic polarization (DP) model The inertial motion (IM) model The bond moment (BM) model The atomic polar tensor (APT) model The ring current mechanism The magnetic field perturbation method (MFP) The sum-over-states vibronic coupling (VC) method Experimental results Raman optical activity (ROA) Introduction Instrumental techniques Theoretical modeis The molecular polarizability and optical activity tensors The bond polarizability model Experimental results Conclusions Foundations and features of infrared reflection techniques (E.-H. Körte and A. Röseler) Introduction Physical background Modelling and evaluation Experimental techniques Specular reflection spectra Spectroscopic ellipsometry Attenuated total reflection Reflection absorption Diffuse reflection Competing techniques Continuous extraction technique (E. Lentz) Introduction The ATR membrane technique ATR membrane cell Basic aspects of ATR theory Selection of the internal reflection dement Selection and preparation of membranes Membrane processes 609

12 XVII Enrichment factor Time constant of the extraction process The Nemst diffusion layer Improvement of the detection limit Alternative membrane procedures Non-reversible enrichment Optical übers covered with membranes Combination of continuous distillation and head space analysis Measurement of the transmission of the membrane Investigation of fast reactions and intermediates (K. Gerwert) Introduction Methods Principles of FTIR Time-resolved FTIR techniques Static FTIR Rapid scan Stroboscope technique Step scan Time-resolved conventional IR techniques Application to bacteriorhodopsin Introduction Sample preparation An example of a static (low temperature) FTIR measurement, the BR to K transition An example for band assignment, the BR to L transition An example of the stroboscope technique: the L to M transition An example of the rapid scan method: the M to BR conversion Application to bacterial photosynthetic reaction centers FT-Raman spectroscopy Application of high-pressure techniques (M. Buback) Introduction Optical cells for vibrational spectroscopy of fluids at high pressures and temperatures Vibrational spectra of polar fluids Chemical transformations in the dense fluid phase studied by high-pressure spectroscopy Low- and high-temperature techniques, spectrometric determination of sample temperature (A. Leipertz and M. Spiekermann) General Temperature determination by IR spectroscopy 664

13 Determining the rotational temperature from the rotational structure of vibration-rotation bands Determination of the rotational temperature of C= Making use of the distance between the maxima of P and R branch Deriving the vibrational temperature from the intensities of overtones and combination bands Temperature determination by simulating band contours The procedure of line reversal IR emission spectra Temperature determination by linear Raman spectroscopy Rotational temperature from the intensity distribution in purely rotational Raman spectra Intensity ratio of two lines in the Stokes wing Taking into account all rotational lines of the Stokes and the anti-stokes wing Determining the vibrational temperature from the intensity distribution of vibrational-rotational Raman bands Temperature determination by simulating band profiles Intensity ratios of vicinal maxima of vibrational transition bands ('hot bands') Ratios of integrated intensities of Stokes and anti-stokes vibrational Raman bands Applications Reaction kinetics Phase transitions Rotational isomerism Unstable substances Carbocations Protonated organic Compounds Intermolecular and intramolecular interactions Macromolecules Coupling of thermogravimetric analysis with IR spectroscopy Character tables Literature Index 765