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Title: Resonant photoelectron spectroscopy of Au{sub 2}{sup −} via a Feshbach state using high-resolution photoelectron imaging

Photodetachment cross sections are measured across the detachment threshold of Au{sub 2}{sup −} between 1.90 and 2.02 eV using a tunable laser. In addition to obtaining a more accurate electron affinity for Au{sub 2} (1.9393 ± 0.0003 eV), we observe eight resonances above the detachment threshold, corresponding to excitations from the vibrational levels of the Au{sub 2}{sup −} ground state (X {sup 2}Σ{sub u}{sup +}) to those of a metastable excited state of Au{sub 2}{sup −} (or Feshbach resonances) at an excitation energy of 1.9717 ± 0.0003 eV and a vibrational frequency of 129.1 ± 1.5 cm{sup −1}. High-resolution photoelectron spectra of Au{sub 2}{sup −} are obtained using photoelectron imaging to follow the autodetachment processes by tuning the detachment laser to all the eight Feshbach resonances. We observe significant non-Franck-Condon behaviors in the resonant photoelectron spectra due to autodetachment from a given vibrational level of the Feshbach state to selective vibrational levels of the neutral final state. Using the spectroscopic data for the ground states of Au{sub 2}{sup −} (X {sup 2}Σ{sub u}{sup +}) and Au{sub 2} (X {sup 1}Σ{sub g}{sup +}), we estimate an equilibrium bond distance of 2.53 ± 0.02 Å for the Feshbach state of Au{sub 2}{supmore » −} by simulating the Franck-Condon factors for the resonant excitation and autodetachment processes.« less
Authors:
; ;  [1]
  1. Department of Chemistry, Brown University, Providence, Rhode Island 02912 (United States)
Publication Date:
OSTI Identifier:
22251416
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Chemical Physics; Journal Volume: 139; Journal Issue: 19; Other Information: (c) 2013 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
74 ATOMIC AND MOLECULAR PHYSICS; 75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; AFFINITY; CROSS SECTIONS; EXCITATION; EXCITED STATES; GROUND STATES; PHOTOELECTRON SPECTROSCOPY; RESOLUTION; RESONANCE