Efficient table-top dual-wavelength beamline for ultrafast transient absorption spectroscopy in the soft X-ray region

TL;DR

This paper introduces a compact soft X-ray beamline capable of ultrafast transient absorption spectroscopy with dual wavelengths, high flux, and sub-11 fs temporal resolution, enabling advanced studies of electronic dynamics in molecules.

Contribution

It presents a novel table-top dual-wavelength soft X-ray beamline with high flux and ultrafast temporal resolution for transient absorption spectroscopy.

Findings

Photon flux of ~2 x 10^7 photons/s/1% bandwidth at 300 eV

Temporal resolution of 11 fs for 800 nm excitation

Successful demonstration of ultrafast spectroscopy in carbon-containing molecules

Abstract

We present a table-top beamline providing a soft X-ray supercontinuum extending up to 350 eV from high-order harmonic generation with sub-13 fs 1300 nm driving pulses and simultaneous production of sub-5 fs pulses centered at 800 nm. Optimization of the high harmonic generation in a long and dense gas medium yields a photon flux of ~2 x 10^7 photons/s/1% bandwidth at 300 eV. The temporal resolution of X-ray transient absorption experiments with this beamline is measured to be 11 fs for 800 nm excitation. This dual-wavelength approach, combined with high flux and high spectral and temporal resolution soft X-ray absorption spectroscopy, is a new route to the study of ultrafast electronic dynamics in carbon-containing molecules and materials at the carbon K-edge.