Freiburg 2024 – wissenschaftliches Programm

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MO: Fachverband Molekülphysik

MO 19: Chirality

MO 19.6: Vortrag

Donnerstag, 14. März 2024, 12:30–12:45, HS 3044

Photoelectrons from transiently populated nonresonant states — •Simon Ranecky, Sudheendran Vasudevan, Han-gyeol Lee, Till Stehling, Nicolas Ladda, Tonio Rosen, Fabian Westmeier, Sagnik Das, Jayanta Ghosh, Hendrike Braun, Arne Senftleben, and Thomas Baumert — Universität Kassel, Institut für Physik und CINSaT, D-34132 Kassel

When an intense laser pulse induces a two-photon electronic transition from one state to another, all other states are populated transiently with various proportions during the interaction time. This transient population in nonresonant states can absorb further photons and then become ionized so that these states become visible in the photoelectron spectrum. This effect was already observed for Sodium atoms [1].

Here, we report the observation of the same ionization mechanism for the first time on molecules using Fenchone and fs- to ns-lasers around 400 nm. The main ionization scheme for this molecule at this wavelength is 2+1 resonance-enhanced multiphoton ionization. And besides the photoelectrons from resonant s- and p-states, we could see photoelectrons from further, nonresonant states.

With this study, we want to encourage spectroscopists to have a close look at the background of their photoelectron spectra. Doing this for Fenchone and observing the weak signals from transiently populated, nonresonant states, we were able to determine the energies of these states.

[1] Krug et al. N.J. Phys. 11 (2009) 105051

Keywords: photoelectron spectroscopy; multiphoton ionization; transient population