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Title: Communication: State-to-state photoionization and photoelectron study of vanadium methylidyne radical (VCH)

By employing the infrared (IR)-ultraviolet (UV) laser excitation scheme, we have obtained rotationally selected and resolved pulsed field ionization-photoelectron (PFI-PE) spectra for vanadium methylidyne cation (VCH{sup +}). This study supports that the ground state electronic configuration for VCH{sup +} is …7σ{sup 2}8σ{sup 2}3π{sup 4}9σ{sup 1} (X{sup ~2}Σ{sup +}), and is different from that of …7σ{sup 2}8σ{sup 2}3π{sup 4}1δ{sup 1} (X{sup ~2}Δ) for the isoelectronic TiO{sup +} and VN{sup +} ions. This observation suggests that the addition of an H atom to vanadium carbide (VC) to form VCH has the effect of stabilizing the 9σ orbital relative to the 1δ orbital. The analysis of the state-to-state IR-UV-PFI-PE spectra has provided precise values for the ionization energy of VCH, IE(VCH) = 54 641.9 ± 0.8 cm{sup −1} (6.7747 ± 0.0001 eV), the rotational constant B{sup +} = 0.462 ± 0.002 cm{sup −1}, and the v{sub 2}{sup +} bending (626 ± 1 cm{sup −1}) and v{sub 3}{sup +} V–CH stretching (852 ± 1 cm{sup −1}) vibrational frequencies for VCH{sup +}(X{sup ~2}Σ{sup +}). The IE(VCH) determined here, along with the known IE(V) and IE(VC), allows a direct measure of the change in dissociation energy for the V–CH as well as the VC–H bond upon removalmore » of the 1δ electron of VCH(X{sup ~3}Δ{sub 1}). The formation of VCH{sup +}(X{sup ~2}Σ{sup +}) from VCH(X{sup ~3}Δ{sub 1}) by photoionization is shown to strengthen the VC–H bond by 0.3559 eV, while the strength of the V–CH bond remains nearly unchanged. This measured change of bond dissociation energies reveals that the highest occupied 1δ orbital is nonbonding for the V–CH bond; but has anti-bonding or destabilizing character for the VC–H bond of VCH(X{sup ~3}Δ{sub 1})« less
Authors:
; ; ; ;  [1]
  1. Department of Chemistry, University of California, Davis, California 95616 (United States)
Publication Date:
OSTI Identifier:
22252854
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Chemical Physics; Journal Volume: 140; Journal Issue: 18; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; CATIONS; DISSOCIATION ENERGY; ELECTRONIC STRUCTURE; EXCITATION; GROUND STATES; PHOTOIONIZATION; VANADIUM; VANADIUM CARBIDES