Near-threshold two-photon double ionization of Kr in the vacuum ultraviolet

Abstract

We report angle-resolved measurements on photoelectrons emitted upon near-threshold two-photon double ionization (TPDI) of Kr irradiated by free-electron laser (FEL) pulses. These photoelectron angular distributions (PADs) are compared with the results of semirelativistic R-matrix calculations. As reported by Augustin et al.[Phys. Rev. A 98, 033408 (2018)], it is found that the presence of autoionizing resonances within the bandwidth of the exciting FEL pulse strongly influences the PADs. In contrast to measurements on lower-Z targets such as Ne and Ar, the larger spin-orbit interaction, inherent in 4p-subshell hole states of Kr, permits us to resolve and study PADs associated with some of the fine-structure components of the Kr + and Kr 2+ ions.

Intense XUV pulses from a compact HHG setup using a single harmonic

“…Intense XUV pulses are also a prerequisite for performing XUV-pump XUV-probe experiments where XUV pulse durations down to the attosecond regime have already been used [15][16][17]. While the study of electron dynamics on these extremely short time scales requires broadband XUV pulses, intense XUV pulses with a narrower bandwidth are advantageous for a range of applications including photoelectron spectroscopy [18,19] and the study of resonant transitions, e.g. within four-wave mixing [20], superfluorescence [21] and the control of Rabi oscillations [22].…”

Intense narrowband XUV pulses from a compact setup

“…Intense XUV pulses are also a prerequisite for performing XUV-pump XUV-probe experiments where XUV pulse durations down to the attosecond regime have already been used [15][16][17]. While the study of electron dynamics on these extremely short timescales requires broadband XUV pulses, intense XUV pulses with a narrower bandwidth are advantageous for a range of applications including photoelectron spectroscopy [18,19] and the study of resonant transitions, e.g. within four-wave mixing [20], superfluorescence [21] and the control of Rabi oscillations [22].…”