Abstract:This study investigates carbon monoxide (CO) adsorption and desorption behaviors on 0.1-0.6-nm-thick Cr-deposited Cu(100) surfaces using infrared reflection absorption (IRRAS) and temperature-programmed desorption (TPD) spectroscopic methods. The low-energy electron diffraction (LEED) pattern for the 0.1-nm-thick Cr-deposited Cu(100) surface indicates that distorted bcc-Cr(110) grows on fcc-Cu(100). The CO exposure to a clean Cu(100) at 90 K produces a single and sharp IR absorption band at 2090 cm À1 that is … Show more
“…However, the bifurcations may shed a light to a different phenomenon. Experimental works reported shoulders in the vibrational spectra that shift or diminish with the coverage [2,5,18,21,24,32]. Two explanations given for this phenomenon are i) the dipole effects, and ii) adsorption of CO on different sites.…”
This work investigates the CO adsorption on the metallic Cu(100) surface using periodic DFT computations. CO adsorption was studied at varying coverages from 1/16 ML to 1/1 ML for a combination of adsorption positions (4-fold, bridge and top). The results showed that adsorption energies are coverage dependent, however, not enough to identify the adsorption site and coverage. However, C-O stretching frequencies are almost unique for studied coverage and adsorption positions. CO adsorption energy changes between -250 kJ/mol to +21 kJ/mol; similarly, the vibrations' range in the 1702 cm -1 to 2110 cm -1 interval, within the studied coverage and adsorption positions. Nevertheless, under the saturation coverage (θCO ≈ 0.55ML) the preferable adsorption site is the on-top position identified with a C-O stretching frequency around ~2100 cm -1 and with ~117 kJ/mol adsorption energy.
“…However, the bifurcations may shed a light to a different phenomenon. Experimental works reported shoulders in the vibrational spectra that shift or diminish with the coverage [2,5,18,21,24,32]. Two explanations given for this phenomenon are i) the dipole effects, and ii) adsorption of CO on different sites.…”
This work investigates the CO adsorption on the metallic Cu(100) surface using periodic DFT computations. CO adsorption was studied at varying coverages from 1/16 ML to 1/1 ML for a combination of adsorption positions (4-fold, bridge and top). The results showed that adsorption energies are coverage dependent, however, not enough to identify the adsorption site and coverage. However, C-O stretching frequencies are almost unique for studied coverage and adsorption positions. CO adsorption energy changes between -250 kJ/mol to +21 kJ/mol; similarly, the vibrations' range in the 1702 cm -1 to 2110 cm -1 interval, within the studied coverage and adsorption positions. Nevertheless, under the saturation coverage (θCO ≈ 0.55ML) the preferable adsorption site is the on-top position identified with a C-O stretching frequency around ~2100 cm -1 and with ~117 kJ/mol adsorption energy.
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