Polarization-dependent laser-induced grating measurements.

The formation of electrostrictive gratings during laser-induced grating (LIG) experiments is considered in an electromagnetic rather than an electrostatic approach. A different form of the relation that was used previously for the electrostrictive pressure was achieved. The theoretical findings were experimentally verified by polarization-dependent LIG spectroscopy measurements of a mixture of nitrogen with methanol vapor at high pressure with 1064-nm radiation. Conditions for suppressing the contribution of the electrostrictive 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 high-density gas mixtures.