Time-Resolved Spectroscopy in Complex Liquids (eBook)

Contents 6
Contributing Authors 8
Preface 10
Chapter 1 TWO DIMENSIONAL FIFTH-ORDER RAMAN SPECTROSCOPY A New Tool for the Study of Liquid State Dynamics 12
1.1 Introduction 13
1.2 Theory 21
1.2.1 Origin of the Fifth-Order Raman Signal 24
1.2.2 Theoretical Results Summary 25
1.3 Experimental Advances 37
1.3.1 Laser Source and Experiment Synopsis 40
1.3.2 Diffractive Optics 42
1.3.3 Heterodyne Detection 45
1.3.4 Multicolor Approach 46
1.3.5 Cascaded Signals 46
1.4 Experimental Findings 51
1.5 General Discussion and Implications of the Findings for the Liquid State 65
1.6 Summary and Future Perspective 71
Acknowledgments 74
References 75
Chapter 2 OPTICAL KERR EFFECT EXPERIMENTS ON COMPLEX LIQUIDS A Direct Access to Fast Dynamic Processes 84
2.1 Introduction 84
2.2 Time-Resolved OKE Experiments 85
2.2.1 A Simple Model 87
2.2.2 The Nonlinear Optics Framework 90
2.3 The Response Function 93
2.3.1 The Linear Susceptibility Tensor and Its Correlation 95
2.3.2 The Model of Liquid Dynamics 99
2.4 The Experimental Procedure 105
2.4.1 Heterodyne Detection 110
2.4.2 HD-OKE vs. Light Scattering Signal 114
2.5 Some Experimental Results 115
2.5.1 HD-OKE in "Simple" Molecular Liquids 115
2.5.2 HD-OKE in Supercooled Liquids and Glass- Formers 122
2.5.3 The Water Case 125
Acknowledgments 128
Appendix: Laser Pulses Definition 128
Notes 130
References 130
Chapter 3 TRANSIENT GRATING EXPERIMENTS IN GLASS- FORMER LIQUIDS A Unique Tool to Investigate Complex Dynamics 139
3.1 Introduction 139
3.2 Theory of the Transient Grating Experiment 141
3.2.1 TG and Four-Wave Mixing 144
3.2.2 Hydrodynamic Approach to the TG Experiments 151
3.3 Experimental Procedure 161
3.3.1 Laser System and Optical Setup 161
3.3.2 Heterodyne and Homodyne Detections 164
3.3.3 Fitting Procedure 166
3.4 Experimental Results 167
3.4.1 SupercooledWater: the Importance of the Photothermal Effect 171
3.4.2 Ortho-terphenyl: the Structural Dynamics of a Fragile Glass-Former 175
3.4.3 Glycerol: A Test of Hydrodynamic Models 180
3.4.4 Meta-Toluidine: The Rotation-Translation Coupling Effect 184
Acknowledgments 188
Appendix: Mathematical Representation of the Stretched Exponential 188
Notes 189
References 190
Chapter 4 DYNAMICAL PROCESSES IN CONFINED LIQUID CRYSTALS 195
4.1 Introduction 195
4.2 Continuum Description of Nematic Liquid Crystals 197
4.3 Fluctuational Dynamics in Nematic Liquid Crystals 199
4.4 Light Scattering by Director Fluctuations 200
4.5 Confined Liquid Crystals 202
4.5.1 Planar Cells 202
4.5.2 Polymer Dispersed Liquid Crystals 203
4.5.3 Holographic Polymer Dispersed Liquid Crystals 203
4.6 Fluctuation Spectrum in Confined Geometries 204
4.6.1 Fluctuation Dynamics in Thin Planar Cells 205
4.6.2 Relaxation Dynamics in PDLCs 209
4.6.3 Relaxation Dynamics in HPDLCs 209
4.7 Dynamic Light Scattering Experiments 210
4.7.1 Planar Samples 211
4.7.2 HPDLCs 216
4.8 Conclusions 222
References 223
Chapter 5 TIME- RESOLVED FLUORESCENCE AND DICHROISM IN ABSORBING LIQUIDS Intermolecular Guest- Host Interactions in Absorbing Liquids 227
5.1 Introduction 227
5.2 Photoinduced Molecular Reorientation of Absorbing Liquids and Liquid Crystals 229
5.3 Theory 233
5.3.1 TRPS fluorescence 234
5.3.2 TRPS Pump-Probe Dichroism 236
5.4 Fluorescence Experiments: Observing the Molecule Rotation in its Excited State 238
5.4.1 Deuterium Effect on Molecular Rotation and its Relationship with Optical Nonlinearity 240
5.4.2 Effect of Excitation-LightWavelength on Dye Excitation and its Relationship with Optical Nonlinearity 243
5.5 Combining Fluorescence and Dichroism Experiments: The Influence of Electronic Excitation on Rotational Friction 246
5.6 Conclusions: The Role of Hydrogen Bonding 249
References 251
Topic Index 256