Broadband cavity-enhanced ultrafast spectroscopy

TL;DR

This paper introduces a cavity-enhanced ultrafast spectroscopy technique that extends broadband optical spectroscopy to dilute gas-phase molecules, achieving high sensitivity and enabling new molecular dynamics studies.

Contribution

It presents a novel cavity-enhanced ultrafast transient absorption spectrometer covering nearly the entire visible range, allowing studies of dilute gas-phase samples with unprecedented sensitivity.

Findings

Achieved detection limit of ΔOD < 1×10^{-9}

Demonstrated transient absorption on molecular systems for excited-state proton transfer

Extended ultrafast spectroscopy to dilute gas-phase molecules and clusters

Abstract

Broadband ultrafast optical spectroscopy methods, such as transient absorption spectroscopy and 2D spectroscopy, are widely used to study molecular dynamics. However, these techniques are typically restricted to optically thick samples, such as solids and liquid solutions. In this article we discuss a cavity-enhanced ultrafast transient absorption spectrometer covering almost the entire visible range with a detection limit of $\Delta$OD $ < 1 \times 10^{-9}$, extending broadband all-optical ultrafast spectroscopy techniques to dilute beams of gas-phase molecules and clusters. We describe the technical innovations behind the spectrometer and present transient absorption data on two archetypical molecular systems for excited-state intramolecular proton transfer, 1'-hydroxy-2'-acetonapthone and salicylideneaniline, under jet-cooled and Ar cluster conditions.