High-resolution photoelectron imaging spectroscopy of cryogenically cooled Fe{sub 4}O{sup −} and Fe{sub 5}O{sup −}
- Department of Chemistry, University of California, Berkeley, California 94720 (United States)
We report high-resolution photodetachment spectra of the cryogenically cooled iron monoxide clusters Fe{sub 4}O{sup −} and Fe{sub 5}O{sup −} obtained with slow photoelectron velocity-map imaging (cryo-SEVI). Well-resolved vibrational progressions are observed in both sets of spectra, and transitions to low-lying excited states of both species are seen. In order to identify the structural isomers, electronic states, and vibrational modes that contribute to the cryo-SEVI spectra of these clusters, experimental results are compared with density functional theory calculations and Franck-Condon simulations. The main bands observed in the SEVI spectra are assigned to the {sup 15}A{sub 2}←{sup 16}B{sub 2} photodetachment transition of Fe{sub 4}O{sup −} and the {sup 17}A′←{sup 18}A″ photodetachment transition of Fe{sub 5}O{sup −}. We report electron affinities of 1.6980(3) eV for Fe{sub 4}O and 1.8616(3) eV for Fe{sub 5}O, although there is some uncertainty as to whether the {sup 15}A{sub 2} state is the true ground state of Fe{sub 4}O. The iron atoms have a distorted tetrahedral geometry in Fe{sub 4}O{sup 0/−} and a distorted trigonal-bipyramidal arrangement in Fe{sub 5}O{sup 0/−}. For both neutral and anionic species, the oxygen atom preferably binds in a μ{sub 2}-oxo configuration along the cluster edge. This finding is in contrast to prior predictions that Fe{sub 5}O{sup 0/−} exhibits a μ{sub 3} face-bound structure.
- OSTI ID:
- 22678970
- Journal Information:
- Journal of Chemical Physics, Vol. 145, Issue 5; Other Information: (c) 2016 Author(s); Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-9606
- Country of Publication:
- United States
- Language:
- English
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