Table-top all-attosecond transient absorption spectroscopy

TL;DR

This paper demonstrates a table-top all-attosecond transient absorption spectroscopy technique using high-harmonic generation, enabling detailed observation of ultrafast electron dynamics in various gases with high resolution and stability.

Contribution

The authors introduce a novel all-attosecond transient absorption spectroscopy method using a table-top HHG source, expanding accessibility and resolution in ultrafast electron dynamics studies.

Findings

Resolved electronic coherences in Xe with 3-fs oscillations

Observed electron dynamics in Kr, Ar, and Ne gases

Validated HHG as a stable, broad-bandwidth source for AATAS

Abstract

Attosecond transient absorption spectroscopy (ATAS) has emerged as a powerful technique within the field of attosecond science, combining extremely high temporal and excellent spectral resolution. So far, ATAS has been implemented in pump-probe experiments where an attosecond extreme-ultraviolet (XUV) pump or probe pulse was combined with a near-infrared (NIR) pulse in the femtosecond range, with the attosecond time resolution deriving from sub-cycle NIR-driven dynamics. Investigations of ultrafast electron dynamics in atoms, molecules and solids, with potential impact across physics, chemistry, and biology, would benefit significantly from the ability to perform all-attosecond transient absorption spectroscopy (AATAS). Here we demonstrate time-resolved AATAS using a table-top high-harmonic generation (HHG) source. The method is applied to investigate previously unresolved electronic coherences in Xe, revealing oscillatory valence hole motion with a 3-femtosecond period. In addition, systematic investigations of electron dynamics in Kr, Ar, and Ne are presented. Our work shows that, thanks to its broad bandwidth, high stability and easy accessibility, HHG is an ideal source for AATAS, offering the potential for replication in numerous laboratories.