Scattering duration time

Relaxation Hierarchy Role of Collisions Scattering Duration Time... 

The key requirements for ISRS excitation are the existence of Raman active phonons in the crystal, and the pulse duration shorter than the phonon period loq1 [19]. The resulting nuclear oscillation follows a sine function of time (i.e., minimum amplitude at t=0), as shown in Fig. 2.2e. ISRS occurs both under nonresonant and resonant excitations. As the Raman scattering cross section is enhanced under resonant excitation, so is the amplitude of the ISRS-generated coherent phonons. 

The risk of relapse in discontinuation trials depends on many non-pharmacological, often poorly controllable factors, notably the expectations of the patients, doctors and nurses, other environmental factors, the duration of hospitalization and prior treatment, and the time interval since the last acute psychotic episode. On the basis of an analysis of 14 discontinuation trials, Kane and Lieberman (1987) found that the relapse rate varied greatly from study to study depending on the trial, relapse rates of 30 86% with clustering around 60 70% have been reported in the first 12 months after placebo substitution. According to Kane and Lieberman, this scatter is a result of the different inclusion criteria applied and the different definitions of relapse . 

The procedure to determine the scattering hysteresis is performed as follows An external field Ea is applied to the crystal along the polar axis for a duration of 10 seconds without illumination. Then the field is switched off. After a relaxation time of 1—2 minutes, which is long enough to reach the steady state of the spontaneous polarization in sbn [45], the crystal is illuminated with the pump beam. The asymmetric scattering pattern builds up and in accordance to the procedure shown above the spatial distribution of the scattered light is investigated in the steady state. 

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