Omiya, Takuma, Kim, Yousoo 
ORCID: 0000-0001-7730-0704, Raval, Rasmita and Arnolds, Heike ORCID: 0000-0002-5723-9309
(2025)
Vibrational Anharmonicity of Carbon Monoxide on Metal Surfaces: Backdonation, Electric Field, and Structure Effects.
The Journal of Physical Chemistry C, 129 (24).
pp. 11024-11030.
ISSN 1932-7447, 1932-7455
Abstract
We investigate the origins of vibrational anharmonicity for CO adsorbed on bare and oxidized Cu(110) and adsorbed to Ruthenium atoms in a Ruthenium tetraphenyl porphyrin (RuTPP) layer on Cu(110) using hot band transitions excited by intense IR-visible sum frequency generation. Observation of both υ = 1 → 2 and υ = 2 → 3 transitions of CO on bare and oxidized Cu(110) shows that the Morse anharmonic oscillator potential does not fully describe the vibrational energy levels. A compilation of our new data and published data on other surfaces shows the expected trend of weaker C-O bonds with lower C-O stretching frequency, being described by more anharmonic potentials. Deviations from this trend reveal changes in the C-O bond that are not captured by its frequency. Coadsorbed oxygen increases the anharmonicity of the C-O bond, likely due to a local electric field (vibrational Stark effect). Anharmonicity of the C-O stretch of CO bound to RuTPP can be tuned by porphyrin coverage, which changes the conformation of the phenyl ligands and influences the adsorbed CO in turn.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | 34 Chemical Sciences, 3406 Physical Chemistry |
| Divisions: | Faculty of Science and Engineering Faculty of Science and Engineering > School of Physical Sciences |
| Depositing User: | Symplectic Admin |
| Date Deposited: | 09 Jul 2025 09:32 |
| Last Modified: | 09 Jul 2025 09:32 |
| DOI: | 10.1021/acs.jpcc.5c03195 |
| Open Access URL: | https://doi.org/10.1021/acs.jpcc.5c03195 |
| Related Websites: | |
| URI: | https://livrepository.liverpool.ac.uk/id/eprint/3193642 |
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