Time-Resolved Ultrafast Transient Polarization Spectroscopy to Investigate Nonlinear Processes and Dynamics in Electronically Excited Molecules on the Femtosecond Time Scale

TL;DR

This paper introduces a new ultrafast spectroscopy technique using a three-pulse polarization scheme to study the nonlinear optical response of excited molecules on femtosecond timescales, providing insights into electronic state dynamics.

Contribution

A novel experimental method employing a non-colinear 3-pulse scheme with heterodyne and homodyne detection for ultrafast polarization spectroscopy of excited molecules.

Findings

Successfully measured third-order nonlinear optical response of excited nitrobenzene

Demonstrated the technique's capability to resolve femtosecond electronic dynamics

Validated the use of optical Kerr effect in time-resolved polarization spectroscopy

Abstract

We report a novel experimental technique to investigate ultrafast dynamics in photoexcited molecules by probing the third-order nonlinear optical susceptibility. A non-colinear 3-pulse scheme is developed to probe the ultrafast dynamics of excited electronic states using the optical Kerr effect by time-resolved polarization spectroscopy. Optical heterodyne and optical homodyne detection are demonstrated to measure the third-order nonlinear optical response for the S1 excited state of liquid nitrobenzene, which is populated by 2-photon absorption of a 780 nm 35 fs excitation pulse.