Vibrational relaxation of M(CO)[sub 6] (M=Cr, Mo, W): Effect of metal mass on vibrational cooling dynamics and non-Boltzmann internal energy distributions

Journal Article · Sun Nov 14 23:00:00 EST 1993 · Journal of Chemical Physics; (United States)

DOI:https://doi.org/10.1063/1.465689· OSTI ID:6048807

King, J C; Zhang, J Z; Schwartz, B J; Harris, C B ^[1]

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1. Department of Chemistry, University of California, Berkeley, California 94720 (United States) Chemical Sciences Division, Lawrence Berkeley Laboratory, Berkeley, California 94720 (United States)

The vibrational relaxation dynamics following the dissociation of C[equivalent to]O from M(CO)[sub 6] (M=Cr, Mo, W) have been studied with picosecond transient absorption spectroscopy. After dissociation of C[equivalent to]O, the pentacarbonyl species forms a complex with a solvent molecule. The cooling of these solvated pentacarbonyl complexes was monitored from 1 ps to 1 ns and different rates for vibrational relaxation were found for each of these three compounds. The W(CO)[sub 5][center dot]S (S=cyclohexane) vibrationally relaxes in 35 ps, whereas Mo(CO)[sub 5][center dot]S relaxes twice as quickly, 18 ps. This result is surprising because the higher density of states in W(CO)[sub 5][center dot]S would be expected to lead to faster cooling of the hot solvated complex. The primary cooling of Cr(CO)[sub 5][center dot]S is completed in 18 ps just as in Mo(CO)[sub 5][center dot]S, but a slower cooling of approximately 150 ps is also present. This component is assigned to vibrational relaxation of the C[equivalent to]O stretching mode. From comparisons with other studies, it appears that the existence of this slower cooling component is present only in first row transition metal carbonyls.

• OSTI ID: 6048807
• Journal Information: Journal of Chemical Physics; (United States), Journal Name: Journal of Chemical Physics; (United States) Vol. 99:10; ISSN JCPSA6; ISSN 0021-9606
• Country of Publication: United States
• Language: English

Related Subjects

664200* -- Spectra of Atoms & Molecules & their Interactions with Photons-- (1992-)
74 ATOMIC AND MOLECULAR PHYSICS
ABSORPTION SPECTRA
CARBON COMPOUNDS
CARBONATES
CHROMIUM
CHROMIUM COMPOUNDS
ELEMENTS
ENERGY LEVELS
EXCITED STATES
MASS NUMBER
METALS
MOLYBDENUM
MOLYBDENUM CARBONATES
MOLYBDENUM COMPOUNDS
OXYGEN COMPOUNDS
REFRACTORY METAL COMPOUNDS
RELAXATION
SPECTRA
TRANSITION ELEMENT COMPOUNDS
TRANSITION ELEMENTS
TUNGSTEN
TUNGSTEN COMPOUNDS
VIBRATIONAL STATES
VISIBLE SPECTRA