Ultrafast Photophysics and Photochemistry in the light of Time-Resolved Coherent Raman spectroscopy

Ultrafast Photophysical and photochemical reactions involve structural and geometrical rearrangements, often accompanied by energy redistribution, which are driven -and can be detected- by coherent interatomic vibrations. Identifying the key normal modes underlying such processes, and the way such vibrational coherences build up, survive and propagate among transient reacting species on the way to the photoproduct, is the main motivation for time-resolved vibrational spectroscopy.

I will provide a few examples of how to exploit the coherent Raman effect, in its frequency (FSRS) and time-domain (IVS) versions, to tackle such problems [1]. These include charge/energy transfer in graphene-based 2D heterostructures [2], ultrafast dynamics in photoexcited heme proteins [3], and orchestrating nuclear dynamics onto targeted electronic states in hybrid perovskites and cristalline moieties [4]. Specifically, I will discuss how to deal with the temporal-spectral resolution trade-off, and how to select and set the appropriate "control knobs" to address physical observables out of reach for conventional spectroscopies, such as absolute molecular geometries in excited states [5].

[1] G. Batignani, C. Ferrante, G. Fumero, M. Martinati and TS, Nature Reviews Methods Primers 4, 34 (2024)
[2] C. Ferrante, G. Di Battista, L.E.P. Lopez, G. Batignani, E. Lorchat, A. Virga, S. Berciaud and TS. PNAS, 119, (2022)
[3] C. Ferrante, E. Pontecorvo, G. Cerullo, M.H. Vos and TS, Nature Chemistry, 8, 1137-1143 (2016).
[4] G. Batignani, G. Fumero, A.R.S. Kandada, G. Cerullo, M. Gandini, C. Ferrante, A. Petrozza, TS, Nature Communications, 9, 1971, (2018)
[5] G. Batignani, E. Mai, G. Fumero, S. Mukamel and TS, Nature communications 13, 7770 (2022)