Forced Rayleigh scattering from non-harmonic gratings applied to complex diffusion processes in glass-forming liquids

Tracer diffusion of 9,10-phenanthrenequinone (PQ) and its photoproduct in s uper-cooled phenolphthalein-dimethyl-ether (PDE) was studied by forced Rayl eigh scattering. In order to investigate the spatial frequency dependence o f the grating dynamics, several spatial harmonics of the grating with non-s inusoidal phase profile produced by non-linear recording were monitored. An optical scheme with a diverging reading beam is proposed for simultaneous reconstruction of the harmonic components. (C) 1999 Elsevier Science B.V. A ll rights reserved.