Interferometric determination of nonlinear refraction of gaseous xenon at lambda=308 nm

The nonlinear contribution to the refractive index of high-pressure xenon a t room temperature at the wavelength of XeCl-laser radiation is measured wi th the help of the Twyman interferometer. Using the dependence of the shift of an interference pattern on the light intensity, the sign and the magnit ude of the nonlinear contribution are measured, which gave Delta n/[F-0(2)] = -6 x 10(-12) electrostatic CGS units. This value is shown to be determin ed by the balance of electrostrictional and electrocaloric mechanisms. It e xceeds the electronic contribution to nonlinear refraction by two orders of magnitude. A possible influence of collisionally induced multiphoton absor ption processes on self-action effects in a high-density gas is discussed.