Long-lived nuclear coherences inside helium nanodroplets

TL;DR

This paper shows that helium nanodroplets provide an exceptionally gentle environment for observing long-lived nuclear coherences in molecules, enabling new insights into molecular dynamics with minimal perturbation.

Contribution

It introduces helium nanodroplets as a novel, low-perturbation medium for time-resolved spectroscopy of molecules, allowing observation of nuclear coherences over extended timescales.

Findings

Vibrational wavepacket motion of In₂ observed for over 50 ps.

Helium nanodroplets reduce environmental perturbation by a factor of 10-100.

Potential to tailor microsolvation environments for diverse studies.

Abstract

Much of our knowledge about dynamics and functionality of molecular systems has been achieved with femtosecond time-resolved spectroscopy. Despite extensive technical developments over the past decades, some classes of systems have eluded dynamical studies so far. Here, we demonstrate that superfluid helium nanodroplets, acting as thermal bath of 0.4 K temperature to stabilize weakly bound or reactive systems, are well suited for time-resolved studies of single molecules solvated in the droplet interior. By observing vibrational wavepacket motion of indium dimers (In$_2$) for over 50 ps, we demonstrate that the perturbation imposed by this quantum liquid can be lower by a factor of 10-100 compared to any other solvent, which uniquely allows to study processes depending on long nuclear coherence in a dissipative environment. Furthermore, tailor-made microsolvation environments inside droplets will enable to investigate the solvent influence on intramolecular dynamics in a wide tuning range from molecular isolation to strong molecule-solvent coupling.