Berrah, Nora: Ultrafast photon induced molecular dynamics using table-top lasers and free electron lasers*

Berrah, Nora: Ultrafast photon induced molecular dynamics using table-top lasers and free electron lasers

Molecules upon photoexcitation can undergo numerous processes leading to changes in their nuclear and electronic structure. Some of these changes can be isomerization, roaming, or in the case of ring molecules, dissociation or ring opening.

We will report on time resolved ultrafast nuclear dynamics initiated by photon excitation and ionization generated from either table-top lasers or free electron lasers (FELs). We have carried out experiments using pump–probe spectroscopy in combination with either coincident Coulomb explosion imaging or photoelectron spectroscopy. Specifically, we will describe different isomerization pathways including roaming in acetonitrile [1] and methanol as well as demonstrate in 2-bromothiophene, two- and three- body molecular fragmentation channels that display dynamics ranging from direct bromine dissociation to ring opening and fragmentation. All measurements are paired with state-of-the-art calculations to identify or interpret the observed mechanisms.  In the case of acetonitrile, theoretical calculations predict unobserved isomerization pathways such as cyclic and unique linear isomers for which we will present preliminary experimental results.

[1] D.Mishra*, A. C. LaForge*, S. Diaz-Tendero, F. Martin, and N. Berrah, Nature Comm. 15, 6656 (2024).

*Work done with D. Mishra, A.C. LaForge, N. Frese, C. Brady, C. Bray, S. Diaz-Tendero, F. Martin, J. Gascon, A. Rossi, M. R. Thomas, N. Golubev, the collaborations of  LCLS proposal No. L10309 and FERMI proposal No. 20234045.