Vibrational coherences in broadband 2D electronic spectroscopy: spectral filtering vs. excited state displacement

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Abstract

Coherences in ultrafast 2D electronic spectroscopy (2DES) reveal superpositions of quantum states corresponding to the motion of wavepackets within the potential energy surface of molecular systems. Whilst electronic coherences imply the transfer of energy between coupled chromophores, vibrational coherences track the motion of nuclear wavepackets, with their intensities governed by the displacement of the electronic excited states with respect to the ground state equilibrium geometry. Analysis of vibrational coherences thus provides valuable information on the ground and excited state structure of molecules, with ground state bleach (GSB) and stimulated emission (SE) pathways reporting on the S0 – S1 displacement and excited state absorption (ESA) pathways also involving an S1 – Sn displacement. Recent development of broadband 2DES experiments have enabled access to a greater range of coherences involving higher energy electronic states. However, a complete analysis must consider involvement of multiple vibrational modes, and any filtering of Liouville pathways due to the finite width of the excitation spectrum. Here, combining the equation of motion-phase matching approach for finite laser spectra with the hierarchical equation of motion to correctly account for dephasing and dissipation, we model half-broadband and broadband 2DES of cresyl violet to demonstrate the impact of spectral filtering vs. the relative displacement of two excited states (S1 and Sn) on the intensity distribution of peaks in the beating maps for two vibrational modes with frequencies 350 cm-1 and 585 cm-1. This study is motivated by recent experimental results from our group which interestingly show the greatest intensity of the beating maps for the 350 cm 1 mode localised in the excited state absorption region.
Original languageEnglish
Number of pages1
Publication statusPublished - 2023
EventTime Resolved Vibrational Spectroscopy 2023 - Amsterdam, Netherlands
Duration: 11 Jun 202316 Jun 2023
Conference number: XXI

Conference

ConferenceTime Resolved Vibrational Spectroscopy 2023
Abbreviated titleTRVS
Country/TerritoryNetherlands
CityAmsterdam
Period11/06/2316/06/23

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