IBER 2023

Probing molecular dynamics using ultrafast XUV transient spectroscopy

6 Sept 2023, 18:35

1h

Department of Physics, University of Coimbra

Poster Communication Poster Session

Speaker

S. Marggi-Poullain (Departamento de Química Física, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, 28040, Madrid, Spain)

Description

Attosecond probing of core-to-valence electronic transitions is a powerful tool for real-time observation of chemical dynamics.[1] Here, ultrafast extreme ultraviolet (XUV) transient absorption spectroscopy is employed to investigate the electronic and nuclear dynamics on small polyatomic iodinated molecules. The dynamics induced by one- or two-photon absorption using either few-femtosecond visible pulses, ranging between 500 nm and 900 nm, or 20-fs UV pulses around 260-280 nm is probed by XUV attosecond isolated pulses through iodine-4d core-to-valence transitions.

This method allows us to directly map in real time the motion of the wavepacket on the excited states, due to the strong shift of the XUV core-to-valence transitions with internuclear separation and the high sensitivity of the wave packet to the electronic configuration. The result presented will involve the direct visualization of time-resolved photodynamics from a diatomic system (I${}_2$) to polyatomic molecules.

First, coherent nuclear motion in the B excited state of molecular iodine is visualized with great detail [2] including the wave packet spreading and later recompression, at the outer and inner turning points, respectively. Second, the photodissociation dynamics of alkyl iodides such as CH${}_3$I, C${}_2$H${}_5$I and C${}_3$H${}_5$I, following one-photon absorption into the A band, is imaged in real-time [3, 4]. In particular, the wave packet bifurcation at the conical intersection is mapped. Structural effects, with special attention to the presence of a double bond, on the dissociation dynamics will be considered.

References
[1] Kobayashi Y et al 2019 Science 375 79
[2] Marggi Poullain S et al 2021 Phys. Rev. A 104 022817
[3] Chang K F et al 2020 Nature Comm. 11 4042.
[4] Chang K F et al 2021 J. Chem. Phys. 154 234301.