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VIBRATIONALLY RESOLVED NEGATIVE ION PHOTOELECTRON SPECTROSCOPIC STUDIES OF BARE TRANSITION METAL TRIMERS

Please use this identifier to cite or link to this item: http://hdl.handle.net/1811/13767

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Title: VIBRATIONALLY RESOLVED NEGATIVE ION PHOTOELECTRON SPECTROSCOPIC STUDIES OF BARE TRANSITION METAL TRIMERS
Creators: Alex, S.; Green, S. M. E.; Leopold, D. G.
Issue Date: 1996
Abstract: We report the 488 nm negative ion photoelectron spectra of the first row transition metal trimers $Cr_{3}$, $V_{3}$ and $V_{2}Ni$, which were prepared in a liquid nitrogen cooled flowing afterglow ion source. The photoelectron transitions to the lowest observed electronic states of $Cr_{3}$, $V_{3}$ and $V_{2}Ni$, which are assumed to be their ground states, each show two active vibrational modes with frequencies ($\pm$$15 cm^{-1}$) in the neutral clusters of 465 and $135 cm^{-1}$ ($Cr_{3}$), 470 and $205 cm^{-1}$ ($V_{3}$), and 415 and $250 cm^{-1}$ ($V_{2}Ni$). For the homonuclear trimers, these are assigned as the totally symmetric stretching and bending modes, respectively, of $C_{2}$, structures. In the mixed early-late transition metal cluster $V_{2}Ni$, the higher frequency mode may involve primarily V-V stretching and the lower one $Ni-V_{2}$ stretching and/or bending. For all three systems, a comparison of the observed stretching frequencies to those of $Cr_{2}$ ($452 cm^{-1}$) and ($530 cm^{-1}$), which have formal bond orders of 6 and 5, respectively, suggest that the triatomic clusters also contain multiple Cr-Cr or V-V bonds. A transition to an excited electronic state of $Cr_{3}$ lying 2850$\pm$20 $cm_{1}$ above its ground state is also observed, accompanied by a long vibrational progression in a (presumably bending) mode with a neutral molecule frequency of 170$\pm$15 $cm_{1}$ in this state. The electron affinities of $Cr_{3}$, $V_{3}$ and $V_{2}Ni$ are determined to be 1.389, 1.103 and 1.112 ($\pm$0.006) eV, respectively.
URI: http://hdl.handle.net/1811/13767
Other Identifiers: 1996-WH-11
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