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UHV studies of the adsorption of small adsorbate molecules on low index platinum single crystals

UHV studies of the adsorption of small adsorbate molecules on low index platinum single crystals
UHV studies of the adsorption of small adsorbate molecules on low index platinum single crystals

The aim of this thesis was to investigate the bonding of small adsorbate molecules to platinum single crystal surfaces using UHV synchrotron far-infrared RAIRS and DFT calculations. The use of UHV synchrotron far-infrared RAIRS enabled the substrate-adsorbate vibration to be observed in a data collection time of a few minutes. The principal adsorbate molecule that was studied was carbon monoxide because of its large infrared absorption factor and its importance in the fuel cell process. DFT calculations were used to confirm the conclusions drawn from the RAIRS experiments. When CO was adsorbed in a c(4 x 2) arrangement on Pt(l 11) at 260 K, two peaks were observed at 376 cm"' and 464 cm"'. These peaks were assigned to the Pt-CO stretch of CO adsorbed in bridge and atop sites respectively. There was no sign of a Fermi resonance in the bridging peak. The distinct difference in the energies of the Pt-CO stretches highlights the sensitivity of the Pt-CO stretching vibration to the local bonding environment Studies were also carried out on the CO induced lifting of the Pt(110)-(1 x2) reconstruction. It was shown that two distinct Pt-CO bands are present depending on whether the CO is bonded to the reconstructed surface (466 to 469 cm"') or the unreconstructed surface (475 to 478 cm"'). The high sensitivity of RAIRS also allowed the lifting of the reconstruction to be detected at a temperature some 50 K lower than previously reported. The first far-infrared RAIRS observation of the Pt-benzene stretch for benzene adsorbed on the Pt(l 10) surface at room temperature is also reported (310 cm"'). Also, an electrochemical transfer system was designed and built onto an existing UHV chamber. This will allow ex-situ experiments, such as cyclic voltammetry, to be used in conjunction with UHV experiments, such as XPS and RAIRS, to better understand the interactions between adsorbates and substrates.

University of Southampton
Baily, Christopher John
Baily, Christopher John

Baily, Christopher John (2003) UHV studies of the adsorption of small adsorbate molecules on low index platinum single crystals. University of Southampton, Doctoral Thesis.

Record type: Thesis (Doctoral)

Abstract

The aim of this thesis was to investigate the bonding of small adsorbate molecules to platinum single crystal surfaces using UHV synchrotron far-infrared RAIRS and DFT calculations. The use of UHV synchrotron far-infrared RAIRS enabled the substrate-adsorbate vibration to be observed in a data collection time of a few minutes. The principal adsorbate molecule that was studied was carbon monoxide because of its large infrared absorption factor and its importance in the fuel cell process. DFT calculations were used to confirm the conclusions drawn from the RAIRS experiments. When CO was adsorbed in a c(4 x 2) arrangement on Pt(l 11) at 260 K, two peaks were observed at 376 cm"' and 464 cm"'. These peaks were assigned to the Pt-CO stretch of CO adsorbed in bridge and atop sites respectively. There was no sign of a Fermi resonance in the bridging peak. The distinct difference in the energies of the Pt-CO stretches highlights the sensitivity of the Pt-CO stretching vibration to the local bonding environment Studies were also carried out on the CO induced lifting of the Pt(110)-(1 x2) reconstruction. It was shown that two distinct Pt-CO bands are present depending on whether the CO is bonded to the reconstructed surface (466 to 469 cm"') or the unreconstructed surface (475 to 478 cm"'). The high sensitivity of RAIRS also allowed the lifting of the reconstruction to be detected at a temperature some 50 K lower than previously reported. The first far-infrared RAIRS observation of the Pt-benzene stretch for benzene adsorbed on the Pt(l 10) surface at room temperature is also reported (310 cm"'). Also, an electrochemical transfer system was designed and built onto an existing UHV chamber. This will allow ex-situ experiments, such as cyclic voltammetry, to be used in conjunction with UHV experiments, such as XPS and RAIRS, to better understand the interactions between adsorbates and substrates.

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Published date: 2003

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Local EPrints ID: 465100
URI: http://eprints.soton.ac.uk/id/eprint/465100
PURE UUID: fef2c78e-a919-4da9-908a-b0675854c278

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Date deposited: 05 Jul 2022 00:23
Last modified: 05 Jul 2022 04:13

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Author: Christopher John Baily

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