Ion TOF spectra of Ne taken at the photon energy of 93.0 eV and the peak intensity of (a) 4 <b>×</b> 10<sup>15</sup> W cm<sup>−2</sup> and (b) 2 <b>×</b> 10<sup>13</sup> W cm<sup>−2</sup> R Guichard M Richter J-M Rost U Saalmann A A Sorokin K Tiedtke 10.6084/m9.figshare.1012461.v1 https://iop.figshare.com/articles/figure/_Ion_TOF_spectra_of_Ne_taken_at_the_photon_energy_of_93_0_eV_and_the_peak_intensity_of_a_4_b_b_10_su/1012461 <p><strong>Figure 2.</strong> Ion TOF spectra of Ne taken at the photon energy of 93.0 eV and the peak intensity of (a) 4 <b>×</b> 10<sup>15</sup> W cm<sup>−2</sup> and (b) 2 <b>×</b> 10<sup>13</sup> W cm<sup>−2</sup>. In the TOF regime below 2.6 μs, the ion intensities were multiplied by a factor of 30.</p> <p><strong>Abstract</strong></p> <p>At the free-electron laser FLASH, multiple ionization of neon atoms was quantitatively investigated at photon energies of 93.0 and 90.5 eV. For ion charge states up to 6+, we compare the respective absolute photoionization yields with results from a minimal model and an elaborate description including standard sequential and direct photoionization channels. Both approaches are based on rate equations and take into account a Gaussian spatial intensity distribution of the laser beam. From the comparison we conclude that photoionization up to a charge of 5+ can be described by the minimal model which we interpret as sequential photoionization assisted by electron shake-up processes. For higher charges, the experimental ionization yields systematically exceed the elaborate rate-based prediction.</p> 2013-08-13 00:00:00 cm model photon energies Photon energy ion charge states rate equations 30. Abstract neon atoms TOF regime photoionization channels ev peak intensity photoionization yields ion intensities intensity distribution sequential photoionization flash laser beam ionization yields Atomic Physics Molecular Physics