Adlayer structure dependent ultrafast desorption dynamics in carbon monoxide adsorbed on Pd (111) [electronic resource]
Desorption; Energy Transfer; Adsorbates; Electroluminescence; Friction.
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| Online Access: |
Online Access (via OSTI) |
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| Corporate Author: | |
| Format: | Government Document Electronic eBook |
| Language: | English |
| Published: |
Washington, D.C. : Oak Ridge, Tenn. :
United States. Department of Energy. Office of Basic Energy Sciences ; distributed by the Office of Scientific and Technical Information, U.S. Department of Energy,
2016.
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| Subjects: |
| Summary: | Desorption; Energy Transfer; Adsorbates; Electroluminescence; Friction. |
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| Abstract: | Here, we report our ultrafast photoinduced desorption investigation of the coverage dependence of substrate–adsorbate energy transfer in carbon monoxide adlayers on the (111) surface of palladium. As the CO coverage is increased, the adsorption site population shifts from all threefold hollows (up to 0.33 ML), to bridge and near bridge (>0.5 to 0.6 ML) and finally to mixed threefold hollow plus top site (at saturation at 0.75 ML). We show that between 0.24 and 0.75 ML this progression of binding site motifs is accompanied by two remarkable features in the ultrafast photoinduced desorption of the adsorbates: (i) the desorption probability increases roughly two orders magnitude, and (ii) the adsorbate–substrate energy transfer rate observed in two-pulse correlation experiments varies nonmonotonically, having a minimum at intermediate coverages. Simulations using a phenomenological model to describe the adsorbate–substrate energy transfer in terms of frictional coupling indicate that these features are consistent with an adsorption-site dependent electron-mediated energy coupling strength, η<sub>el</sub>, that decreases with binding site in the order: three-fold hollow > bridge and near bridge > top site. This weakening of η<sub>el</sub> largely counterbalances the decrease in the desorption activation energy that accompanies this progression of adsorption site motifs, moderating what would otherwise be a rise of several orders of magnitude in the desorption probability. Within this framework, the observed energy transfer rate enhancement at saturation coverage is due to interadsorbate energy transfer from the copopulation of molecules bound in three-fold hollows to their top-site neighbors. |
| Item Description: | Published through SciTech Connect. 07/01/2016. "bnl--112726-2016-ja" "KC0301050" Journal of Chemical Physics 145 1 ISSN 0021-9606; JCPSA6 AM. Sung -Young Hong; Pan Xu; Nina R. Camillone; Michael G. White; Nicholas Camillone, III. |
| Physical Description: | Article No. 014704 : digital, PDF file. |