Real-time observation of electronic, vibrational, and rotational dynamics in nitric oxide with attosecond soft X-ray pulses at 400 eV

TL;DR

This paper demonstrates a novel high-harmonic generation-based transient absorption spectroscopy at 400 eV, enabling real-time observation of electronic, vibrational, and rotational dynamics in nitric oxide molecules with element and electronic state specificity.

Contribution

It introduces the first HHG-based TAS at the nitrogen K-edge (400 eV) to observe comprehensive molecular dynamics in nitric oxide at attosecond to picosecond scales.

Findings

Successful measurement of electronic, vibrational, and rotational dynamics

First demonstration of TAS at 400 eV for molecules

Reveals element-specific molecular behavior in photochemical reactions

Abstract

Photoinduced quantum dynamics in molecules have hierarchical temporal structures with different energy scales that are associated with electron and nuclear motions. Femtosecond-to-attosecond transient absorption spectroscopy (TAS) using high-harmonic generation (HHG) with a photon energy below 300 eV has been a powerful tool to observe such electron and nuclear dynamics in a table-top manner. However, comprehensive measurements of the electronic, vibrational, and rotational molecular dynamics have not yet been achieved. Here, we demonstrate HHG-based TAS at the nitrogen K-edge (400 eV) for the first time, and observe all the electronic, vibrational, and rotational degrees of freedom in a nitric oxide molecule at attosecond to sub-picosecond time scales. This method of employing core-to-valence transitions offers an all-optical approach to reveal complete molecular dynamics in photochemical reactions with element and electronic state specificity.