6533b829fe1ef96bd128ac3b

RESEARCH PRODUCT

Wavelength dependence of multiphoton ionization of xenon

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description

We have studied the multiphoton ionization of xenon atoms by $160\phantom{\rule{0.3em}{0ex}}\mathrm{fs}$ pulses at intensities of $5\ifmmode\times\else\texttimes\fi{}{10}^{12}$ and $1.3\ifmmode\times\else\texttimes\fi{}{10}^{13}\phantom{\rule{0.3em}{0ex}}\mathrm{W}∕{\mathrm{cm}}^{2}$ 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 $700\phantom{\rule{0.3em}{0ex}}\mathrm{nm}$. Resonant and nonresonant processes as well as channel switching effects have been observed in this intensity and wavelength regime. Mainly resonant $(5+1)$-photon ionization via $ns$, $nd$, and $n{d}^{\ensuremath{'}}$ Rydberg states was studied in the region of $505--602\phantom{\rule{0.3em}{0ex}}\mathrm{nm}$. Resonance structures were found related to the two fine structure ionization channels ${\mathrm{Xe}}^{+}\phantom{\rule{0.2em}{0ex}}^{2}P_{3∕2}$ and ${\mathrm{Xe}}^{+}\phantom{\rule{0.2em}{0ex}}^{2}P_{1∕2}$. In addition the $(6+1)$-photon resonant ionization and nonresonant 5- and 6-photon processes could be studied.