Kristjan Kunnus: Probing of coherent nuclear wavepacket dynamics with X-ray emission and scattering in solvated Fe photosensitizers

Spin and oxidation state sensitivity of 3d metal K-edge X-ray Emission Spectroscopy (XES) has been utilized in recent years to successfully probe the ultrafast spin transition and electron transfer processes in femtosecond time-resolved experiments [1,2]. In this talk I will present the results from a combined time-resolved Fe Kα and Kβ XES and X-ray Solution Scattering (XSS) experiment at the LCLS where we investigated photoinduced dynamics in a molecular Fe photosensitizer [Fe(bmip)2]2+ (bmip = 2,6-bis(3-methyl-imidazole-1-ylidine)-pyridine) [3]. Simultaneous tracking of electronic and nuclear structure allowed us to determine branching of electronic relaxation pathways and observe coherent nuclear dynamics. In particular, I will discuss the origin of vibronic effects in time-resolved XES experiments and explain how these lead to the sensitivity of XES from nuclear wavepacket dynamics [4].

References:

1. Zhang et al., Nature 7, 629 (2014).
2. K. S. Kjær et al., Chem. Sci. 10, 5749-5760 (2019).
3. K. Kunnus et al., Nat. Commun. 11, 634 (2020). https://doi.org/10.1038/s41467-020-14468-w
4.  M. Vacher et al., Struct. Dyn. 7, 044102 (2020). https://doi.org/10.1063/4.0000022