Beat-frequency-resolved two-dimensional electronic spectroscopy: disentangling vibrational coherences in artificial fluorescent proteins with sub-10-fs visible laser pulses

TL;DR

This paper introduces a beat-frequency-resolved 2D electronic spectroscopy technique using sub-10-fs visible laser pulses to analyze vibrational coherences in artificial fluorescent proteins, providing detailed vibrational information.

Contribution

It develops a highly stable ultrashort laser source and a measurement method to resolve vibrational coherences in 2D spectra with high temporal resolution.

Findings

Successfully extracted vibrational peaks behind inhomogeneous broadening.

Resolved vibrational quantum beats in the excited electronic state.

Demonstrated the effectiveness of sub-10-fs pulses in vibrational coherence analysis.

Abstract

We perform a beat-frequency-resolved analysis for two-dimensional electronic spectroscopy using a high-speed and stable 2D electronic spectrometer and few-cycle visible laser pulses to disentangle the vibrational coherences in an artificial fluorescent protein. We develop a highly stable ultrashort light source that generates 5.3-fs visible pulses with a pulse energy of 4.7 uJ at a repetition rate of 10 kHz using multi-plate pulse compression and laser filamentation in a gas cell. The above-5.3-fs laser pulses together with a high-speed multichannel detector enable us to measure a series of 2D electronic spectra, which are resolved in terms of beat frequency related to vibrational coherence. We successfully extract the discrete vibrational peaks behind the inhomogeneous broadening in the absorption spectra and the vibrational quantum beats of the excited electronic state behind the strong stationary signal in the typical 2D electronic spectra.