Speaker
Description
Solvated electrons play important roles in the origin and formation of radiation damage in biological tissue as well as for large-scale chemical synthesis, where they are used as strong reducing agents. While in the former case solvated electrons are created by the interaction of liquids with ionizing radiation, in the latter case they are typically produced by the dissolution of alkali metals in liquid ammonia. These sodium ammonia solutions with their many peculiar concentration dependent properties[1,2] are not well understood on a molecular level, despite the many studies conducted on them[1-4]. Molecular clusters of ammonia doped with sodium atoms can serve as useful model systems, enabling the use of gas phase photoelectron and photoion spectroscopic techniques[4-7].
I will present our recent photoelectron photoion coincidence study of small mixed sodium ammonia clusters[7] in which we could, with support from quantum chemical calculations, identify different electron transfer processes occurring after excitation with UV and VUV radiation. Among these processes, the formation of transient solvated dielectrons and their subsequent decay via an electron-transfer mediated decay process constitutes a direct observation of solvated dielectrons and an intriguing source of low-energy electrons. In a second part I will discuss preliminary results from a time-resolved photoelectron spectroscopy study on large sodium-doped ammonia clusters performed at the LDM endstation of the free electron Laser Fermi, indicating the presence of additional autoionization pathways following the XUV ionization of these clusters.
[1] Zurek, E., P.P. Edwards, and R. Hoffmann. Angew. Chem. Int. Ed., 2009. 48(44)
[2] Buttersack, T., P.E. Mason, R.S. McMullen, et al. Science, 2020. 368(6495)
[3] Vöhringer, P. Annu. Rev. Phys. Chem., 2015. 66(1)
[4] Hartweg, S., A.H.C. West, B.L. Yoder, et al. Angew. Chem. Int. Ed., 2016. 55(40)
[5] Zeuch, T. and U. Buck. Chem. Phys. Lett., 2013. 579
[6] West, A.H.C., B.L. Yoder, D. Luckhaus, et al. J. Phys. Chem. Lett., 2015. 6(8)
[7] Hartweg, S., J. Barnes, B.L. Yoder, et al. Science, 2023. 380(6650)
