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Figure 5
Ionization dynamics simulated with the plasma code CRETIN. (a) Average ionization per C, S and Fe atoms, as a function of time during the pulse, for two photon energies (6.86 keV and 7.36 keV). Ionization saturates faster for light atoms. For Fe it is dominated by collisional ionization. (b) Scattering power for C, S and Fe ions as a function of time, estimated from the number of bound electrons (without atomic form factors). (c) Expected accumulated signal during the pulse due to the loss of scattering power for C, S and Fe ions, compared with the neutral undamaged atoms (black dashed line). (d) Calculated dose rate (MGy fs−1) in the sample as a function of time, for two photon energies. The dose rate decreases during exposure due to saturation in ionization and changes in the photoionization cross sections. (e) Absorption coefficient for Fe and S in the sample as a function of time. The drastic change in absorption for Fe above the K-edge in the first 20 fs is due to a rapid loss of electrons and a lowering of the ionization potential in the plasma environment.

Journal logoJOURNAL OF
SYNCHROTRON
RADIATION
ISSN: 1600-5775
Volume 22| Part 2| February 2015| Pages 225-238
doi:10.1107/S1600577515002349
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