Dynamic Behavior of Atoms and Molecules Irradiated by Intense X-rays of SACLA

Abstract

We have investigated ultrafast electronic and nuclear dynamics in atoms, molecules and clusters induced by very intense（～50 μJ/μm²）, ultrashort（～10 fs） pulses generated by SACLA. At photon energy of 5.0～5.5 keV, we could identify that Xeⁿ⁺ with n up to 26 is produced, evidencing occurrence of deep inner-shell ionization and sequential electronic decay cycles repeated multiple times in the xenon atom within ～10 fs pulse duration. The results for momentum-resolved multiple ion coincidence study on iodine-contained organic molecules（iodomethane and 5-iodouracil）illustrates that the charges are produced by the cycles of deep inner-shell ionization of the iodine atom and sequential electronic decay and spread over the entire molecule within 10 fs, leading to Coulomb explosion. The measured momentum distributions and correlations are well reproduced by the model calculations. The results for electron spectroscopy on argon and xenon clusters, with help of model calculations, illustrate that nanoplasma is formed by the XFEL pulse in tens of fs, and continuous thermal emission from the plasma occurs in ps.