Probing The Vibrational Wave Packet Dynamics On The Electronic Ground State Of Neutral Silver Tetramer: Vibrational Frequencies, Anharmonicities And Anisotropy

Jin, Jiaye

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https://hdl.handle.net/2142/116884 Copy

Description

Title

Probing The Vibrational Wave Packet Dynamics On The Electronic Ground State Of Neutral Silver Tetramer: Vibrational Frequencies, Anharmonicities And Anisotropy

Author(s)

Jin, Jiaye

Contributor(s)

• Asmis, Knut R.
• Grellmann, Max

Issue Date

2022-06-20

Keyword(s)

Mini-symposium: Spectroscopy meets Chemical Dynamics

Abstract

Small silver clusters possess remarkable luminescence and photoelectric properties, making them subject of current research.\footnote{Grandjean, D. et al. Science 2018, 361, 686–690.} However, obtaining vibrations on small, neutral silver clusters remain challenging, due to difficulties in mass-selecting neutral clusters and a lack of easily accessible and widely wavelength-tunable far infrared light sources. Here, we report our study on experimentally probing the vibrational wave packet dynamics on the ground state potential energy surface of the neutral silver tetramer Ag$_{4}$, a benchmark system for small neutral metal clusters, and unambiguously assign its structure. We combine femtosecond pump-probe spectroscopy employing the NeNePo (negative-neutral-positive) excitation scheme\footnote{Wolf, S. et al., Phys. Rev.Lett. 74(21), 4177; Hess, H. et al., Eur. Phys. J. D, 16(1), 145-149.} with a cryogenic ion-trap tandem mass spectrometer. A linear polarized ultrafast pump pulse ($\sim$40 fs, tunable center wavelength from 700 nm - 820 nm) is used to selectively prepare a coherent wave packet by photodetachment from thermalized (20 - 300 K) Ag$_4^-$ anions. The wave packet dynamics on the electronic ground state are then probed using a second polarized ultrafast pulse ($\sim$50 fs, centered at 400 nm), which ionizes Ag$_4$ in a two-photon process. The mass-selected cation yield as a function of the delay time (0 - 60 ps) between the two laser pulses yields the fs-NeNePo spectrum. Frequency analysis with a resolution down to about 0.5 cm$^{-1}$ by using Fourier transform of transient traces reveal one prime frequency band (109.5 $\pm$ 0.4 cm$^{-1}$) in all conditions and four bands at 32 cm$^{-1}$, 78 cm$^{-1}$, 186 cm$^{-1}$ and 295 cm$^{-1}$ dependent on pump wavelengths and temperatures. These frequencies are consists with predicted fundamental vibration frequencies (\nub{1}, \nub{2}, \nub{5} and \nub{6}) and one combination (\nub{1} + \nub{2}) for rhombic D$_{\rm{2h}}$ geometry of Ag$_4$. The rephrasing period of the wave packet allows determining vibrational anharmonicities. A strong dependence of the NeNePo cation signal on the polarization of ultrafast pulses is observed, revealing information on the anisotropy of the partial waves involved in the photodetachment process.

Publisher

International Symposium on Molecular Spectroscopy

Type of Resource

text

Language

eng

Handle URL

https://hdl.handle.net/2142/116884

DOI

https://doi.org/10.15278/isms.2022.MH05

Copyright and License Information

Copyright 2022 held by the authors

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