Extreme-ultraviolet pump-probe studies of one femtosecond scale electron dynamics

TL;DR

This paper demonstrates a novel method using extreme-ultraviolet pump-probe techniques to directly observe electron dynamics on the femtosecond to attosecond timescale, overcoming previous intensity limitations in XUV spectroscopy.

Contribution

It introduces a new approach that enables efficient two-XUV-photon absorption, allowing for the study of atomic coherences and pulse durations at attosecond resolution.

Findings

Successful probing of atomic coherences at 1 fs scale

Determination of XUV pulse duration with high precision

Applicability of the method to complex atomic systems

Abstract

Studies of ultrafast dynamics along with femtosecond-pulse metrology rely on non-linear processes, induced solely by the exciting/probing pulses or the pulses to be characterized. Extension of these approaches to the extreme-ultraviolet (XUV) spectral region opens up a new, direct route to attosecond scale dynamics. Limitations in available intensities of coherent XUV continua kept this prospect barren. The present work overcomes this barrier. Reaching condition at which simultaneous ejection of two bound electrons by two-XUV-photon absorption becomes more efficient than their one-by-one removal it is succeeded to probe atomic coherences, evolving at the 1fs scale, and determine the XUV-pulse duration. The investigated rich and dense in structure autoionizing manifold ascertains applicability of the approach to complex systems. This initiates the era of XUV-pump-XUV-probe experiments with attosecond resolution.