%0 Figure %A Guichard, R %A Richter, M %A Rost, J-M %A Saalmann, U %A A Sorokin, A %A Tiedtke, K %D 2013 %T Ion TOF spectra of Ne taken at the photon energy of 93.0 eV and the peak intensity of (a) 4 × 1015 W cm−2 and (b) 2 × 1013 W cm−2 %U 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 %R 10.6084/m9.figshare.1012461.v1 %2 https://iop.figshare.com/ndownloader/files/1480283 %K cm %K model %K photon energies %K Photon energy %K ion charge states %K rate equations %K 30. Abstract %K neon atoms %K TOF regime %K photoionization channels %K ev %K peak intensity %K photoionization yields %K ion intensities %K intensity distribution %K sequential photoionization %K flash %K laser beam %K ionization yields %K Atomic Physics %K Molecular Physics %X

Figure 2. Ion TOF spectra of Ne taken at the photon energy of 93.0 eV and the peak intensity of (a) 4 × 1015 W cm−2 and (b) 2 × 1013 W cm−2. In the TOF regime below 2.6 μs, the ion intensities were multiplied by a factor of 30.

Abstract

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.

%I IOP Publishing