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Chemisorption of carbon monoxide on the iridium(111) surface: In situ studies of adsorption and desorption kinetics via vibrational spectroscopy

Journal Article · · Industrial and Engineering Chemistry Research
DOI:https://doi.org/10.1021/ie950747b· OSTI ID:376239
; ; ; ;  [1]
  1. Univ. of California, Santa Barbara, CA (United States). Dept. of Chemical Engineering
The IR absorption peak position of the CO intramolecular stretching vibration, measured with Fourier transform infrared reflection-absorption spectroscopy, has been employed for the first time as a nonintrusive coverage probe to study the adsorption of CO on Ir(111). The observed temperature and coverage dependence of the adsorption probability is consistent with an extrinsic precursor model. Isobars were obtained under steady-state conditions for pressures ranging from 10{sup {minus}9} to 10{sup {minus}5} Torr. Isosteres were constructed from these data and used to determine both isosteric heats of adsorption and the adsorbate entropy as functions of coverage. The isosteric heat of adsorption decreased from 44 {+-} 2 kcal/mol at 0.05 ML to 37 {+-} 1 kcal/mol at 0.6 ML. A pronounced decrease in the binding energy at 0.35 ML is attributed to near-neighbor CO repulsions. The entropy of the adsorbate layer indicates two ordering regions which correspond to the formation of the specific overlayer structures.
OSTI ID:
376239
Journal Information:
Industrial and Engineering Chemistry Research, Journal Name: Industrial and Engineering Chemistry Research Journal Issue: 9 Vol. 35; ISSN IECRED; ISSN 0888-5885
Country of Publication:
United States
Language:
English

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