Practical Raman Spectroscopy: An Introduction

Raman spectroscopy is a molecular spectroscopic technique, which in recent years has attracteda lot of attention as a versatile analytical technique, with applications in a broad range of research areas. Practical Raman Spectroscopy: An Introduction provides the reader with: background information on the technique, an overview of theoretical aspects explanations of possible interferences and enhancement effects. The author walks the reader through the key components of common Raman spectroscopy instrumentation and explains the basic principles of post–processing of Raman spectra, mathematical filters, spectral interpretation, quantitative aspects, searching algorithms, Raman mapping, etc. The text: is enhanced with practical examples from research, illustrating the broad field of applications includes Questions and Discussion Topics, where the reader can evaluate their understanding provides a comprehensive bibliography to guide the reader to more specialized texts and sources. Rather than overwhelming the reader in mathematical discussions and equations, the author provides an intuitive feeling for different concepts in Raman spectroscopy. Thus, this book aims to provide an introduction to students as well as to the occasional user, who wants to gain a broader knowledge of the technique.

Preface xi Acknowledgements xiii Acronyms, Abbreviations and Symbols xv About the Author xvii Introduction to Raman spectroscopy xix 1 Theoretical Aspects 1 1.1 Classical Approach 1 1.2 Selection Rule 7 1.3 Energy Levels and Group Frequencies 13 1.4 Raman Intensity 19 1.5 Raman Bandwidth 35 1.6 The General Appearance of a Raman Spectrum 37 1.7 Summary 38 Intermezzo 1.1 The Harmonic Oscillator and the Position of the Vibrational Energy Levels 6 Intermezzo 1.2 The Anharmonic Oscillator and the Position of Vibrational Energy Levels 11 Intermezzo 1.3 Raman Intensity Annotations 30 2 Interferences and Side–effects 39 2.1 Absorption 40 2.2 Fluorescence 40 2.3 Thermal Effects, Photodecomposition and Laser Ablation 43 2.4 Ambient Light and Background Radiation 44 2.5 Summary 44 3 Enhancement of the Raman Signal 47 3.1 Resonance Raman (RR) Spectroscopy 48 3.2 Surface–Enhanced Raman Spectroscopy (SERS) 48 3.3 Summary 59 Intermezzo 3.1 The Analysis of Organic Dyes by SERS 58 4 Raman Instrumentation 61 4.1 Lasers 62 4.2 Detectors 74 4.3 Filters 81 4.4 Dispersion Systems 83 4.5 Components for Transportation of Light 88 4.6 Sample Chambers and Measurement Probes 91 4.7 Noise in Raman Spectroscopy 95 4.8 Summary 99 5 Raman Spectroscopy in Daily Lab–life 101 5.1 Calibration of a Raman Spectrometer 102 5.2 Raman Spectral Post–processing 108 5.3 Interpretation of Raman Spectra of Organic Molecules 116 5.4 Interpretation of Raman Spectra of Inorganic Molecules 131 5.5 Quantitative Aspects of Raman Spectroscopy 134 5.6 Fingerprinting and Spectral Searching Algorithms 137 5.7 Raman Mapping and Imaging 141 5.8 Combination with Other Techniques 145 5.9 Summary 147 Intermezzo 5.1 Micro–Raman Spectroscopy in Microbiology 107 Intermezzo 5.2 Raman Spectroscopy in a Forensics Laboratory 117 Intermezzo 5.3 Pigment Analysis with Raman Spectroscopy 132 Intermezzo 5.4 Detection of Counterfeit Medicines with Raman Spectroscopy 136 Intermezzo 5.5 Exobiology: Raman Spectroscopy Helps the Search for Life on Mars 139 Intermezzo 5.6 Direct Analysis of Precious Art Objects 144 Responses to Questions 149 Bibliography 153 Glossary of Terms 155 SI Units and Physical Constants 157 Periodic Table 163 Index 165

Peter Vandenabeele , Ghent University, Belgium