Nonlinear Optical Probes and Processes in Polymers and Liquid ...

2.19 Speed of the PR decay as a function of the shallow detrapping rate β1. 88
3.1 Materials used in this study . . . . . . . . . . . . . . . . . . . . . . . 109
3.2 Experimental set-up for xerographic discharge technique . . . . . . . 116
3.3 Typical experimental data from the xerographic discharge measurement.118
3.4 Electric field dependence of the photogeneration cross-section . . . . . 121
3.5 Experimental set-up for the time-of-flight (TOF) technique . . . . . . 123
3.6 Example of a current pulse as observed in PVK with the TOF technique126
3.7 Current transients as observed in PVK using TOF technique at various
temperatures at the electric field 30 V/µm. . . . . . . . . . . . . . . . 129
3.8 Dependence of the mobility on the electric field . . . . . . . . . . . . 130
3.9 Dependence of the mobility on temperature . . . . . . . . . . . . . . 131
3.10 Current transients at various temperatures . . . . . . . . . . . . . . . 133
3.11 Experimental set-up for DC photoconductivity measurements . . . . 134
3.12 Typical photocurrent transients observed on the short time scale DC
photoconductivity experiment . . . . . . . . . . . . . . . . . . . . . . 137
3.13 Example of the photocurrent transient analysis . . . . . . . . . . . . 139
3.14 Trapping parameter γT MT 1 as a function of illumination intensity I0 . 141
3.15 Long time scale photocurrent dynamics . . . . . . . . . . . . . . . . . 143
3.16 Example of the photocurrent dynamics analysis at long time scales . 145
3.17 Experimental set-up for the two-beam coupling experiment. . . . . . 147
3.18 Typical data for the 2BC experiment . . . . . . . . . . . . . . . . . . 148
3.19 Electric field dependence of the gain coefficient for p- and s-polarized
beams at various temperatures . . . . . . . . . . . . . . . . . . . . . . 152
3.20 Ratio of the gain coefficients for p- and s-polarized incident beams as
a function of temperature . . . . . . . . . . . . . . . . . . . . . . . . 152
3.21 Experimental set-up used in the FWM experiment. . . . . . . . . . . 154
3.22 Typical transient of the diffracted signal (I4) as observed in the FWM
experiment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 156
3.23 Electric field dependence of the diffraction efficiency . . . . . . . . . . 158
3.24 Temperature dependence of the diffracted signal . . . . . . . . . . . . 160
3.25 Dependence of the diffraction efficiency on the modulation parameter m162
3.26 Dependence of the faster component of the PR speed ν1 on the electric
field . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 165
3.27 Schematic representation of the PR grating decay . . . . . . . . . . . 167
3.28 Dependence of the faster component of the PR decay on the electric
field for various intensities of erasing beam. . . . . . . . . . . . . . . . 169
3.29 Schematic representation of the PR composite with different chromophores.
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 173
3.30 Intensity dependence of the faster PR speed for different composites . 183
ix