Polarization-dependent laser-induced grating measurements

The formation of electrostrictive gratings during laser-induced grating (LI G) experiments is considered in an electromagnetic rather than an electrost atic approach. A different form of the relation that was used previously fo r the electrostrictive pressure was achieved. The theoretical findings were experimentally verified by polarization-dependent LIG spectroscopy measure ments of a mixture of nitrogen with methanol vapor at high pressure with 10 64-nm radiation. Conditions for suppressing the contribution of the electro strictive grating relative to that of the simultaneously generated thermal grating signals were found theoretically and experimentally. The technique can potentially increase detection sensitivity for population gratings in h igh-density gas mixtures. (C) 1999 Optical Society of America.