Analytical Raman Spectroscopy

Transcription

1 Analytical Raman Spectroscopy Edited by JEANETTE G. GRASSELLI Department of Chemistry Ohio University Athens, Ohio and BERNARD J. BULKIN BP Research Centre Sunbury-on-Thames Middlesex, England A WILEY-INTERSCIENCE PUBLICATION JOHN WILEY & SONS, INC. New York / Chichester / Brisbane / Toronto / Singapore

2 CONTENTS CHAPTER 1 THE RAMAN EFFECT: AN INTRODUCTION 1 Bernard J. Bulkin 1.1. Background Classical Description of Raman Spectroscopy Result of Quantum Mechanical Treatment of Raman Scattering Selection Rules: Contrasting IR and Raman Spectra Depolarization Ratios Resonance Raman Effect Nonlinear Raman Effects Guide to the Literature of Raman Spectroscopy CHAPTER 2 MODERN RAMAN INSTRUMENTATION AND TECHNIQUES D. Bruce Chase Introduction Components of Modern Raman Spectrometers Sources Continuous Wave Lasers Pulsed Lasers Lenses and Filters Collection Optics Dispersihg Optical Elements: Monochromators Detection Systems Single-Channel Systems IX

3 X CONTENTS Multichannel Systems Computers in Detection Systems 2.3. Sample Handling General Microsampling 2.4. Problems: Fluorescence and Thermal Sample Degradation 2.5. Fourier Transform Raman Spectroscopy Components Examples of the Advantages of Fourier Transform Raman Measurements Problems 2.6. Future Efforts 2.7. Addendum Lasers Lenses and Filters Monochromators Detectors Microsampling FT-Raman Spectroscopy CHAPTER 3 EXPERIMENTAL CONSIDERATIONS FOR ACCURATE POLARIZATION MEASUREMENTS 45 James R. Scherer 3.1. Introduction 3.2. Tools for Tuning 3.3. Light Path Geometry 3.4. Sample Container 3.5. Polarization Scrambler 3.6. The Analyzer 3.7. Polarization Orientation of the Excitation Laser Beam 3.8. Standard Raman Measurement

4 CONTENTS XI CHAPTER 4 RAMAN SPECTROSCOPY OF INORGANIC SPECIES IN SOLUTION 59 Donald E. Irish and Toru Ozeki 4.1. Introduction Identification of Inorganic Species in Solution Präsentation of the Raman Spectrum Interpretation Quantitative Analysis Correlating Raman Intensities and Species Concentrations Spectral Analysis with Bandfitting Programs Factor Analysis The GAUSS-Z Program Raman Difference Spectroscopy Conclusion 90 Appendix 91 Acknowledgments CHAPTER 5 QUANTITATIVE ANALYSIS BY RAMAN SPECTROSCOPY 107 Thomas J. Vickers and Charles K. Mann 5.1. Introduction Historical Development Variations in Source, Sample, and Optics: Effect on Quantitative Analyses Ordinate Errors Abscissa Errors Data Treatment Multichannel Versus Scanning Measurements Fluorescence and Raman Measurements Comparison of Raman and IR Measurements for Quantitative Analysis 127

5 Xll CONTENTS CHAPTER Solvent Behavior Emission Versus Absorption Experimental Flexibility Experimental Comparison of Sensitivity 130 Acknowledgments CHARACTERIZATION OF SEMICONDUCTORS BY RAMAN SPECTROSCOPY 137 Fred H. Pollak 6.1. Introduction General Background of Raman Scattering, Particularly Relating to Crystalline Solids Polarizability Theory of Raman Scattering Second-Order Raman Scattering Lattice Polarizability Including Free Carrier Effects Fano Effect Polarization Selection Rules Atomic Displacement Effects Linear-q and Surface Electric Field-Induced Effects Dispersion Relations for Lattice Vibrations Instrumentation Silicon and Other Group IV Semiconductors Microcrystalline Geometries Structural and Crystallization Effects in a-si, a-ge, and a-c Ion Damage and Laser Annealing Reactive Ion Etching Strain Effects The Metal/Si Interface Laser Writing of Si Microstructures Temperature Probe Binary Zincblende Semiconductors 180

6 CONTENTS Carrier Concentration and Space/Charge Layer Effects Microcrystalline Effects Symmetry-Forbidden Transverse Optical Mode Scattering Ion Implantation and Annealing Process-Induced Damage 6.6. Alloy Semiconductors Alloy Composition Alloy Potential Fluctuations Optic Phonons Disorder-Activated Zone-Edge Phonons Ion Implantation and Annealing Carrier Concentration Hg^Cd^Te Heterojunctions Two-Phonon Raman Scattering 6.7. Surface Films Including Oxides Xlll CHAPTER 7 POLYMER APPLICATIONS 223 Bernard J. Bulkin 7.1. Introduction Raman Spectrum of Polyethylene terephthalate) Vibrational Analysis of Polymers as a Foundation to Understanding Sensitivity of the Raman Spectrum to Conformational Change Low-Frequency (< 200cm" l ) Spectra Features in the Spectra of Fibers Considerations in Selecting Spectroscopic Parameters for Comparing Spectra Orientation, Conformation, and Crystallinity Amorphous Orientation and Low-Frequency Spectra Derivation of Polymer Specific Heats 244

7 XIV CONTENTS CHAPTER A Guide to Other Raman Studies of Polymers Conclusion ANISOTROPIC SCATTERING PROPERTIES OF UNIAXIALLY ORIENTED POLYMERS: RAMAN STUDIES John F. Rabolt 8.1. Introduction 8.2. Experimental Scattering Geometry 8.3. Geometrie Considerations 8.4. Symmetry Considerations 8.5. Example: Planar Zigzag Poly(vinylidene fluoride) Acknowledgment CHAPTER 9 ORGANIC AND PETROCHEMICAL APPLICATIONS OF RAMAN SPECTROSCOPY 275 Donald L. Gerrard 9.1. Introduction Organic and Petrochemical Sample-Handling Techniques Versatility and Simplicity Owing to the Scattering Process Glass Sample Containers and Aqueous Systems Excitation Using Visible Lasers Useof Fiber Optics Characterization of Nonpolar Groups Quantitative Studies Internal Standard Method Reacting Systems Spatial Resolution: Raman Microscopy Methods of Signal Enhancement Resonance-Enhanced Raman

8 CONTENTS XV Spectroscopy and Applications in Organic and Petrochemical Systems Surface-Enhanced Raman Spectroscoy and Applications Electrochemical Applications Colloids Metal-Island Films General Analytical Applications for Organic Materials Time-Resolved Studies: Examples of In Situ Studies of Reacting Systems Homopolymerization of Styrene Homopolymerization of Methyl Methacrylate Copolymerizations and Multicomponent Polymerizations: The Use of Mathematical Deconvolution Other Applications Fluorescence in Organic Systems Fluorescence Reduction Sample Purißcation "Burning Out" with the Laser Beam The Use of UV and Near-IR Lasers Fluorescence-Quenching Agents Anti-Stokes Raman Spectroscopy Extraction of the Raman Signal from the Fluorescence Background Background Subtraction Use of Picosecond Pulsing and Gating Nonlinear Raman Spectroscopy Conclusions CHAPTER 10 RAMAN SPECTROSCOPY IN CATALYSTS 325 Mehmed Mehicic and Jeanette G. Grasselli Introduction Advantages of Raman Spectroscopy in Catalytic Studies 325

9 XVI CONTENTS Miscellaneous Applications Zeolites Hydrodesulfurization Catalysts Mo0 3 -Based Catalysts Background and Preparation Variables Promoter (Cobalt-Containing) Structures Promoter (Nickel-Containing) Structures Activated (Sulfided) Molybdenum-Containing Catalysts Conclusion W0 3 -Based Catalysts Oxidation Catalysis Vanadium Oxide Catalysts Manganese Oxide Catalysts Bismuth Molybdate Catalysts Iron Oxide Catalysts Other Systems Metathesis Catalysis Olefin Hydrogenation Syngas Processes Fischer-Tropsch Catalysis Hydroformylation Catalysis Methanation Olefin Dehydrogenation CHAPTER 11 RAMAN SPECTROSCOPY FOR BIOLOGICAL APPLICATIONS 397 Pham V. Huong Introduction Specific Problems in Biological Studies Identification of Biomolecules 398

10 CONTENTS XV Structure in Aqueous Solutions Dynamics and Interactions Instrumentation and Procedures Structures Raman Spectra of Living Organisms/Tissues/Cells Eye Lens Biological Membranes Raman Spectra of Isolated Biomolecules Structures and Conformations of t-rna Structures in Solutions and Solids Endo-melting (Ordered to Disordered State) Conformation Transitions Between Ordered States Molecular Dynamics Interactions Selective Enhancement of Raman Bands Corresponding to the Interaction Site of Hemoglobin Changes in the Active Site of Hemoglobin with Interactions a-helical and Random-Coil Structures in Proteins Mechanisms Vision Transmission in Nervo us Systems Protonation of Biomolecules S H/S S Conversion Carcinogenesis Conclusions Acknowledgments

11 XV111 CHAPTER 12 CONTENTS CHEMICAL APPLICATIONS OF GAS-PHASE RAMAN SPECTROSCOPY 425 William F. Murphy Introduction Experimental Aspects Instrumentation Source Sample Irradiation Sample Cells Transfer Optics Monochromator and Detector Instrumental Calibration Frequency Calibration Intensity Response Calibration Applications Theoretical Background Methodology Measurement of Species Abundance Measurement of Temperature Survey of Applications Combustion Diagnostics Remote Sensing Analytical Applications Conclusions INDEX 452