Journal article 230 views
Vibrational excitation of adsorbed molecules by photoelectrons of very low energy: acrylonitrile on Cu (100)
J Tornero,
H.H Telle,
G García,
A. González Ureña,
Helmut Telle
Physical Chemistry Chemical Physics, Volume: 13, Issue: 18
Swansea University Author: Helmut Telle
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DOI (Published version): 10.1039/c0cp01869d
Abstract
In this study, we report on a powerful method of primary photoelectron scattering by adsorbed species. Specifically, threshold-energy (E<sub>kin,max</sub> < 0.5 eV) two-photon photoelectrons (2PPE) are used to probe acrylonitrile (ACN) molecules chemisorbed onto a Cu(100) substrate, h...
Published in: | Physical Chemistry Chemical Physics |
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ISSN: | 1463-9076 1463-9084 |
Published: |
2011
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Online Access: |
Check full text
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URI: | https://cronfa.swan.ac.uk/Record/cronfa7172 |
Abstract: |
In this study, we report on a powerful method of primary photoelectron scattering by adsorbed species. Specifically, threshold-energy (E<sub>kin,max</sub> < 0.5 eV) two-photon photoelectrons (2PPE) are used to probe acrylonitrile (ACN) molecules chemisorbed onto a Cu(100) substrate, held at room temperature. This has proven to constitute a perfect tool to reveal the ACN vibrational modes in the chemisorbed state. From the dynamics of the directional (perpendicular to the copper surface) electron energy loss we conclude that only a few fundamental vibrational motions of adsorbed ACN are excited, namely the C=C, C<triple-bond>N and C–H stretch modes. From the excitation probability spectra threshold energies, Eth, of these modes was extracted: E<sub>th</sub>(C=C) = 182(15) meV, E<sub>th</sub>(C<triple-bond>N) = 248(16) meV – which are shifted noticeably from the equivalent gas phase values; and E<sub>th</sub>(C–H) ~ 360–380 meV – which varies only marginally from the gas phase value. The interpretation of the excitation spectra suggests that the di-sigma adsorption configuration of the terminal C- and N-atoms dominates, which agrees well with the orientation and bindings predicted in Density Functional Theory (DFT) calculations. Consistent with this is the observation that the contribution to the 2PPE excitation spectra from the C–H stretch motion is by far the largest, which are not directly affected by chemisorption bonding. |
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College: |
Faculty of Science and Engineering |
Issue: |
18 |