Erlangen 2022 – scientific programme

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MO: Fachverband Molekülphysik

MO 13: Femtosecond Spectroscopy III

MO 13.2: Talk

Wednesday, March 16, 2022, 14:45–15:00, MO-H5

Femtosecond-NeNePo Spectroscopy of Small Silver Clusters — •Max Grellmann, Jiaye Jin, Jürgen Jäschke, Marcel Jorewitz, and Knut R. Asmis — Wilhelm-Ostwald-Institut für Physikalische und Theoretische Chemie, Universität Leipzig, Linnéstrasse 2, D-04103 Leipzig, Germany

Vibrational spectroscopy on mass-selected neutral silver clusters is still difficult to be performed due to a lack of efficient methods to directly select a single mass for neutral species in the gas-phase and rare intense and tunable far infrared sources in the vibrational frequency range of metal-metal bonds.

Here, we present experimental results probing the wave packet dynamics on the electronic ground state potential energy surface of the neutral silver tetramer by using femtosecond pump-probe spectroscopy via three charge states, so-called NeNePo (negative-neutral-positive) spectroscopy. Silver clusters are produced in a liquid nitrogen cooled magnetron sputter source. Mass-selected silver tetramer anions are accumulated in a gas-filled ion trap, thermalized to 20 K and subsequently photodetached using an 800 nm ultrafast pump pulse. The wave packet dynamics are then probed using a second, photoionizing ultrafast 400 nm probe pulse. The so produced signal of silver tetramer cations (and its fragments) is monitored mass-selectively as a function of the laser pulses delay time, yielding a NeNePo spectrum. Frequency analysis by Fourier transform reveals evidence for the time-dependent excitation of all six vibrational modes and the time scale of intramolecular vibrational energy redistribution processes.