Quantum interference spectroscopy of RbHe exciplexes formed on helium nanodroplets

TL;DR

This study uses femtosecond pump-probe photoionization to observe quantum interference in Rb atoms and RbHe exciplexes on helium nanodroplets, revealing vibrational structures and dynamics of these transient molecules.

Contribution

It demonstrates quantum interference effects in Rb and RbHe molecules on helium nanodroplets and introduces a method to analyze vibrational dynamics during molecule formation.

Findings

Observation of quantum interference fringes in Rb+ ion yield

Identification of vibrational structure in RbHe exciplexes

Real-time tracking of vibrational energy evolution during formation

Abstract

Femtosecond multiphoton pump-probe photoionization is applied to helium nanodroplets doped with rubidium (Rb). The yield of Rb+ ions features pronounced quantum interference (QI) fringes demonstrating the coherence of a superposition of electronic states on a time scale of tens of picoseconds. Furthermore, we observe QI in the yield of formed RbHe exciplex molecules. The quantum interferogram allows to determine the vibrational structure of these unstable molecules. From a sliced Fourier analysis one can not only extract the population dynamics of vibrational states but also follow their energetic evolution during the RbHe formation.