Electron energy loss and thermal desorption spectroscopy of pyridine adsorbed on Pt(111)
The chemisorption behavior of pyridine (NC/sub 5/H/sub 5/) on a Pt(111) surface has been examined by using thermal desorption and electron energy loss spectroscopy as a function of adsorption temperature. The vibrational spectrum of pyridine adsorbed to room temperature on this surface shows intense loss peaks in the specular direction from vibrational modes which can be characterized as in-plane stretching and bending modes. This vibrational spectrum has been interpreted as the formation of an ..cap alpha..-pyridyl species (NC/sub 5/H/sub 4/) on the surface. The pyridyl moiety is bonded to the platinum surface through the nitrogen and one of the ..cap alpha..-carbon atoms with the pyridyl plane perpendicular to the metal surface. When pyridine is adsorbed at low temperature (120 K), it bonds to the surface through both the nitrogen atom and the ..pi.. and ..pi../sup */ orbitals of the pyridine ring. As the crystal is warmed to 260 K, at saturation coverage, approximately 50% of the molecules desorb as molecular pyridine. The remaining pyridine molecules partially decompose on the surface to form an ..cap alpha..-pyridyl fragment. The electron energy loss spectra of pyridine adsorbed at both low and room temperature is compared to the infrared spectra of two osmium cluster compounds: Os/sub 3/(CO)/sub 11/(NC/sub 5/H/sub 5/), a pyridine complex, and HOs/sub 3/(CO)/sup 18/NC/sub 5/H/sub 4/), a pyridyl complex.
- Research Organization:
- Lawrence Berkeley Lab., CA
- DOE Contract Number:
- AC03-76SF00098
- OSTI ID:
- 6909542
- Journal Information:
- J. Phys. Chem.; (United States), Vol. 90:22
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
PLATINUM
MONOCRYSTALS
SORPTIVE PROPERTIES
PYRIDINE
CHEMISORPTION
DESORPTION
DEUTERIUM COMPOUNDS
ENERGY-LOSS SPECTROSCOPY
EXPERIMENTAL DATA
INFRARED SPECTRA
TEMPERATURE EFFECTS
VIBRATIONAL STATES
AZINES
CHEMICAL REACTIONS
CRYSTALS
DATA
ELECTRON SPECTROSCOPY
ELEMENTS
ENERGY LEVELS
EXCITED STATES
HETEROCYCLIC COMPOUNDS
HYDROGEN COMPOUNDS
INFORMATION
METALS
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PLATINUM METALS
PYRIDINES
SEPARATION PROCESSES
SORPTION
SPECTRA
SPECTROSCOPY
SURFACE PROPERTIES
TRANSITION ELEMENTS
400201* - Chemical & Physicochemical Properties