Electronic excitation of Rh{sup I}(CO){sub 2} species on Al{sub 2}O{sub 3} surfaces: Photodissociation of the Rh{sup I}-CO bond
- Univ. of Pittsburgh, PA (United States)
The photoexcitation of Rh{sup I}(CO){sub 2}/Al{sub 2}O{sub 3} has been studied by infrared and ultraviolet absorption spectroscopy. A photodissociation energy threshold between 2.8 and 2.9 eV, for the Rh{sup I}-CO bond of the Rh{sup I}(CO){sub 2} species, has been determined by monitoring the depletion of the CO moiety, leading to the production of a highly active surface site. A Rh{sup I}-CO photodissociation cross section of 3.6 {times} 10{sup {minus}20} cm{sup 2} photon{sup {minus}1} and a quantum efficiency of 0.01 [Rh{sup I}-CO dissociation] photon{sup {minus}1} has been estimated for the initial stages of Rh{sup I}(CO){sub 2} photodepletion. Three absorption bands, observed at 3.3, 3.9, and 4.6 eV in the ultraviolet absorption spectra, are assigned to electronic transitions from filled Rh d-character molecular orbitals to d-character and/or ligand-based antibonding orbitals. Photodissociation of the Rh{sup I}-CO bond occurs from the direct excitation of Rh{sup I}(CO){sub 2} species. During later stages of photolysis, the role of depletion of Rh{sup I}(CO){sub 2} decreases dramatically and this effect may be due to the slow diffusion of CO through the pores of the Al{sub 2}O{sub 3} support.
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- OSTI ID:
- 316054
- Journal Information:
- Journal of Physical Chemistry B: Materials, Surfaces, Interfaces, amp Biophysical, Journal Name: Journal of Physical Chemistry B: Materials, Surfaces, Interfaces, amp Biophysical Journal Issue: 51 Vol. 102; ISSN 1089-5647; ISSN JPCBFK
- Country of Publication:
- United States
- Language:
- English
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