Resonantly enhanced multiphoton ionization of xenon in Bessel beams

Resonantly enhanced multiphoton ionization of xenon near the three-photon 6s resonance has been studied under the excitation by the Bessel beams. It has been shown that the ionization spectra are significantly different in the cases of the Bessel and the Gaussian laser beams. This difference is caused by an internal third-harmonic field, which in the Bessel beam is generated in a wide spectral range due to the self-phase-matching mechanism. The cancellation of the 6s resonance in the Bessel beam has been demonstrated. Similar to the case of the Gaussian beams the canceled resonance appears in the spectra under the excitation by counterpropagating Bessel beams. The origin of some features in the ionization spectra is discussed.