Determination of optical constants in noble gases through multiphoton ionization measurements

A multiphoton ionization technique involving third-harmonic generation in phase-matched mixtures of noble gases has been used to make accurate determinations of oscillator strengths for transitions from the ground state to 6s, 6s, 5d, and 7s levels in Xe and to the 5s level of Kr. The method also allows determinations to be made of the absorption coefficients for third-harmonic photons generated in noble-gas mixtures and the vacuum-uv refractive index for the positively dispersive buffer-gas component of the medium, all in the same experiment. The effects of low concentrations of dimers on refractive indexes are also demonstrated. Results are compared with data from other experimental techniques.