Key points are not available for this paper at this time.
Competition between third-harmonic generation and multiphoton ionization in xenon is confirmed in a direct experiment using counterpropagating circularly polarized laser beams to suppress third-harmonic emission. Three-photon resonantly enhanced multiphoton ionization through the 6s and 6s^' levels in xenon, previously reported to disappear at pressures above a few Torr, gives rise to sharp intense ionization signals under these conditions.
Glownia et al. (Mon,) studied this question.