Wavelength dependence of multiphoton ionization of xenon

International audienceWe have studied the multiphoton ionization of xenon atoms by 160 fs pulses at intensities of 531012 and 1.331013 W/cm2 and present photoelectron kinetic energy and angular distribution spectra measured with a photoelectron imaging spectrometer. A noncollinear optical parametric amplifier allows us to tune the wavelength of the laser pulse over a range between 500 and 700 nm. Resonant and nonresonant processes as well as channel switching effects have been observed in this intensity and wavelength regime. Mainly resonant s5+1d-photon ionization via ns, nd, and nd8 Rydberg states was studied in the region of 505–602 nm. Resonance structures were found related to the two fine structure ionization channels Xe+ 2P3/2 and Xe+ 2P1/2. In addition the s6+1d-photon resonant ionization and nonresonant 5- and 6-photon processes could be studied