# Coherent multidimensional spectroscopy in the gas phase

## TL;DR

This paper reviews recent advances in gas-phase multidimensional coherent spectroscopy, highlighting new phase-cycling techniques and their application to studying ultrafast molecular dynamics in cold, dilute samples.

## Contribution

It introduces refined phase-cycling methods and demonstrates their use in probing femtosecond dynamics of molecules in helium droplets, revealing fundamental excitation and charge transfer processes.

## Key findings

- Successful application of 2D spectroscopy to doped helium droplets
- Observation of femtosecond electronic dynamics in cold molecules
- Potential to isolate fundamental molecular processes in low-temperature environments

## Abstract

Recent work applying multidimentional coherent electronic spectroscopy at dilute samples in the gas phase is reviewed. The development of refined phase-cycling approaches with improved sensitivity has opened-up new opportunities to probe even dilute gas-phase samples. In this context, first results of 2-dimensional spectroscopy performed at doped helium droplets reveal the femtosecond dynamics upon electronic excitation of cold, weakly-bound molecules, and even the induced dynamics from the interaction with the helium environment. Such experiments, offering well-defined conditions at low temperatures, are potentially enabling the isolation of fundamental processes in the excitation and charge transfer dynamics of molecular structures which so far have been masked in complex bulk environments.