Internal reflection and ATR spectroscopy

 Content: Preface xiii   1 Introduction to Spectroscopy 1   1.1 History 1  1.2 Definition of Transmittance and Reflectance 6  1.3 The Spectroscopic Experiment and the Spectrometer 10  1.4 Propagation of Light through a Medium 13  1.5 Transmittance and Absorbance 15  1.6 S/N in a Spectroscopic Measurement 16   2 Harmonic Oscillator Model for Optical Constants 20   2.1 Harmonic Oscillator Model for Polarizability 20  2.2 Clausius--Mossotti Equation 25  2.3 Refractive Index 26  2.4 Absorption Index and Concentration 29   3 Propagation of Electromagnetic Energy 31   3.1 Poynting Vector and Flow of Electromagnetic Energy 31  3.2 Linear Momentum of Light 34  3.3 Light Absorption in Absorbing Media 35  3.4 Lambert Law and Molecular Cross Section 36   4 Fresnel Equations 39   4.1 Electromagnetic Fields at the Interface 39  4.2 Snell's Law 41  4.3 Boundary Conditions at the Interface 42  4.4 Fresnel Formulae 43  4.5 Refl ectance and Transmitance of Interface 44  4.6 Snell's Pairs 46  4.7 Normal Incidence 47  4.8 Brewster's Angle 47  4.9 The Case of the 45degree Angle of Incidence 48  4.10 Total Internal Reflection 49   5 Evanescent Wave 55   5.1 Exponential Decay and Penetration Depth 55  5.2 Energy Flow at a Totally Internally Reflecting Interface 58  5.3 The Evanescent Wave in Absorbing Materials 59   6 Electric Fields at a Totally Internally Reflecting Interface 61   6.1 Ex, Ey, and Ez for s-Polarized Incident Light 61  6.2 Ex, Ey, and Ez for p-Polarized Incident Light 62   7 Anatomy of ATR Absorption 67   7.1 Attenuated Total Reflection (ATR) Reflectance for s- and p-Polarized Beam 67  7.2 Absorbance Transform of ATR Spectra 69  7.3 Weak Absorption Approximation 70  7.4 Supercritical Reflectance and Absorption of Evanescent Wave 73  7.5 The Leaky Interface Model 76   8 Effective Thickness 79   8.1 Defi nition and Expressions for Effective Thickness 79  8.2 Effective Thickness and Penetration Depth 80  8.3 Effective Thickness and ATR Spectroscopy 82  8.4 Effective Thickness for Strong Absorptions 84   9 Internal Reflectance near Critical Angle 85   9.1 Transition from Subcritical to Supercritical Reflection 85  9.2 Effective Thickness and Refractive Index of Sample 87  9.3 Critical Angle and Refractive Index of Sample 88   10 Depth Profiling 92   10.1 Energy Absorption at Different Depths 92  10.2 Thin Absorbing Layer on a Nonabsorbing Substrate 93  10.3 Thin Nonabsorbing Film on an Absorbing Substrate 94  10.4 Thin Nonabsorbing Film on a Thin Absorbing Film on a Nonabsorbing Substrate 94   11 Multiple Interfaces 97   11.1 Reflectance and Transmittance of a Two-Interface System 97  11.2 Very Thin Films 100  11.3 Interference Fringes 101  11.4 Normal Incidence 102  11.5 Interference Fringes and Transmission Spectroscopy 104  11.6 Thin Films and ATR 108  11.7 Internal Reflection: Subcritical, Supercritical, and in between 109  11.8 Unusual Fringes 110  11.9 Penetration Depth Revisited 113  11.10 Reflectance and Transmittance of a Multiple Interface System 116   12 Metal Optics 121   12.1 Electromagnetic Fields in Metals 121  12.2 Plasma 126  12.3 Reflectance of Metal Surfaces 127  12.4 Thin Metal Films on Transparent Substrates 130  12.5 Curious Reflectance of Extremely Thin Metal Films 132  12.6 ATR Spectroscopy through Thin Metal Films 134   13 Grazing Angle ATR (GAATR) Spectroscopy 136   13.1 Attenuated Total Refl ection (ATR) Spectroscopy of Thin Films on Silicon Substrates 136  13.2 Enhancement for s- and p-Polarized Light 137  13.3 Enhancement and Film Thickness 139  13.4 Electric Fields in a Very Thin Film on a Si Substrate 141  13.5 Source of Enhancement 143  13.6 GAATR Spectroscopy 145   14 Super Grazing Angle Reflection Spectroscopy (SuGARS) 147   14.1 Reflectance of Thin Films on Metal Substrates 147  14.2 Problem of Reference 148  14.3 Sensitivity Enhancement 150   15 ATR Experiment 151   15.1 Multiple Reflection Attenuated Total Reflection (ATR) 151  15.2 Facet Reflections 155  15.3 Beam Spread and the Angle of Incidence 156  15.4 Effect of Facet Shape 158  15.5 Beam Spread and the Number of Reflections in Multiple Refl ection ATR 160  15.6 Effect of Beam Alignment on Multiple Reflection ATR 162  15.7 Change in the Refractive Index of the Sample due to Concentration Change 166   16 ATR Spectroscopy of Small Samples 168   16.1 Benefits of Attenuated Total Reflection (ATR) for Microsampling 168  16.2 Contact Problem for Solid Samples 170   17 Surface Plasma Waves 172   17.1 Excitation of Surface Plasma Waves 172  17.2 Effect of Metal Film Thickness on Reflectance 173  17.3 Effect of the Refractive Index of Metal on Reflectance 174  17.4 Effect of the Absorption Index of Metal on Reflectance 174  17.5 Use of Plasmons for Detecting Minute Changes of the Refractive Index of Materials 175  17.6 Use of Plasmons for Detecting Minute Changes of the Absorption Index of Materials 178   18 Extraction of Optical Constants of Materials from Experiments 180   18.1 Extraction of Optical Constants from Multiple Experiments 180  18.2 Kramers--Kronig Relations 184  18.3 Kramers--Kronig Equations for Normal Incidence Reflectance 187   19 ATR Spectroscopy of Powders 192   19.1 Propagation of Light through Inhomogeneous Media 192  19.2 Spectroscopic Analysis of Powdered Samples 193  19.3 Particle Size and Absorbance of Powders 195  19.4 Propagation of Evanescent Wave in Powdered Media 198   20 Energy Flow at a Totally Internally Reflecting Interface 209   20.1 Energy Conservation at a Totally Reflecting Interface 209  20.2 Speed of Propagation and the Formation of an Evanescent Wave 212   21 Orientation Studies and ATR Spectroscopy 214   21.1 Oriented Fraction and Dichroic Ratio 214  21.2 Orientation and Field Strengths in Attenuated Total Reflection (ATR) 217   22 Applications of ATR Spectroscopy 220   22.1 Solid Samples 220  22.2 Liquid Samples 220  22.3 Powders 221  22.4 Surface-Modified Solid Samples 221  22.5 High Sample Throughput ATR Analysis 221  22.6 Process and Reaction Monitoring 222  Appendix A ATR Correction 224  Appendix B Quantification in ATR Spectroscopy 227  Index 237
 Abstract:             
              Attenuated Total Reflection (ATR) spectroscopy is the most frequently used sampling technique for infrared spectroscopy, enabling samples to be examined in solid or liquid states. This book shows how ATR is used for materials that are either too thick or strong to be analyzed by other methods.                 Read more...