CO and CO/sub 2/ decomposition on bulk polycrystalline alkali metals

Journal Article · Thu Dec 01 04:00:00 EST 1988 · J. Phys. Chem.; (United States)

DOI:https://doi.org/10.1021/j100335a026· OSTI ID:6188924

Paul, J; Hoffmann, F M; Robbins, J L

Electron energy loss spectra and thermal desorption traces of CO and CO/sub 2/ adsorbed on bulk polycrystalline alkali-metal films are presented. Carbon monoxide adsorbs with low probability (< 10/sup /minus/3/) at 100 K, and the bound molecular state is characterized by a vibrational band at 1750 cm/sup /minus/1/. The C-O bond dissociates as a result of CO-alkali-metal interaction below 250 K. Annealing to higher temperatures causes alkali-metal desorption, and the further path of the dissociated species relates to the specific chemistry of the substrate onto which the alkali-metal film was evaporated. Carbon dioxide adsorbs with high probability (/approx equal/1) on alkali metals at 100 K. A mixture of oxalate ions and weakly adsorbed molecular CO/sub 2/ is observed. Molecular CO/sub 2/ is characterized by vibrational structure at 650 and 2350 cm/sup /minus/1/ and by desorption below 150 K. The oxalate ions show intense bands at 1650, 1350, and 920 cm/sup -1/. Annealing causes a gradual replacement of the above bands with bands at 1100 and 1450 cm/sup /minus/1/. These bands indicate the formation of carbonate ions. Further annealing results in gradual carbonate decomposition and oxide formation. This step is substrate dependent. The authors observe the simultaneous release of CO/sub 2/, CO, and alkali-metal atoms at 540 K following CO/sub 2/ exposure but also the prerelease of CO around 470 K. Finally, they emphasize that all CO and CO/sub 2/ experiments were performed on quenched alkali-metal films since preannealing results in coalescence of the alkali metal, which opens up patches of monolayer coverage.

• Research Organization: Exxon Research and Engineering Company, Annandale, NJ (USA)
• OSTI ID: 6188924
• Journal Information: J. Phys. Chem.; (United States), Journal Name: J. Phys. Chem.; (United States) Vol. 92:24; ISSN JPCHA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical &amp; Physicochemical Properties
ALKALI METALS
ANNEALING
CARBON COMPOUNDS
CARBON DIOXIDE
CARBON MONOXIDE
CARBON OXIDES
CATALYSIS
CATALYSTS
CATALYTIC EFFECTS
CHALCOGENIDES
CHEMICAL REACTIONS
DATA
DECOMPOSITION
ELECTRON SPECTROSCOPY
ELEMENTS
ENERGY LEVELS
ENERGY-LOSS SPECTROSCOPY
EXCITED STATES
EXPERIMENTAL DATA
HEAT TREATMENTS
HIGH TEMPERATURE
INFORMATION
LOW TEMPERATURE
MEDIUM TEMPERATURE
METALS
NUMERICAL DATA
OXIDES
OXYGEN COMPOUNDS
POTASSIUM
SODIUM
SPECTROSCOPY
THERMAL ANALYSIS
VIBRATIONAL STATES