High-repetition-rate and high-photon-flux 70 eV high-harmonic source for coincidence ion imaging of gas-phase molecules

TL;DR

This paper introduces a high-repetition-rate, high-flux 70 eV high-harmonic source driven by a 100 kHz fiber laser, enabling advanced time-resolved molecular imaging with table-top setups.

Contribution

The development of a novel high-harmonic source with record photon flux and repetition rate for coincidence ion imaging of molecules.

Findings

Achieved 10^11 photons/sec at 68.6 eV in a 1.3 eV bandwidth harmonic.

Demonstrated coincidence measurements on CH3I molecules.

Outlined future prospects for ultrafast molecular dynamics studies with this source.

Abstract

Unraveling and controlling chemical dynamics requires techniques to image structural changes of molecules with femtosecond temporal and picometer spatial resolution. Ultrashort-pulse x-ray free-electron lasers have significantly advanced the field by enabling advanced pump-probe schemes. There is an increasing interest in using table-top photon sources enabled by high-harmonic generation of ultrashort-pulse lasers for such studies. We present a novel high-harmonic source driven by a 100 kHz fiber laser system, which delivers 10$^{11}$ photons/s in a single 1.3 eV bandwidth harmonic at 68.6 eV. The combination of record-high photon flux and high repetition rate paves the way for time-resolved studies of the dissociation dynamics of inner-shell ionized molecules in a coincidence detection scheme. First coincidence measurements on CH$_3$I are shown and it is outlined how the anticipated advancement of fiber laser technology and improved sample delivery will, in the next step, allow pump-probe studies of ultrafast molecular dynamics with table-top XUV-photon sources. These table-top sources can provide significantly higher repetition rates than the currently operating free-electron lasers and they offer very high temporal resolution due to the intrinsically small timing jitter between pump and probe pulses.