Sulphur overlayers on the Au(1 1 0) surface: LEED and TPD study |
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Authors: | Sergey A. Krasnikov Greg Hughes Attilio A. Cafolla |
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Affiliation: | a School of Physical Sciences, Dublin City University, Glasnevin, Dublin 9, Ireland b Institute for Advanced Material Science (IAMS), Trinity College Dublin, Dublin 2, Ireland c National Centre for Sensor Research (NCSR), Dublin City University, Glasnevin, Dublin 9, Ireland |
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Abstract: | The adsorption and desorption of sulphur on the clean reconstructed Au(1 1 0)-(1 × 2) surface has been studied by low energy electron diffraction, Auger electron spectroscopy and temperature programmed desorption. The results obtained show a complex behaviour of the S/Au(1 1 0) system during sulphur desorption at different temperatures. Two structures of the stable ordered sulphur overlayer on the Au(1 1 0) surface, p(4 × 2) and c(4 × 4), were found after annealing the S/Au(1 1 0) system at 630 K and 463 K, respectively. The corresponding sulphur coverage for these overlayers was estimated by AES signal intensity analysis of the Au NOO and S LMM Auger lines to be equal to 0.13 ML and 0.2 ML, respectively. Both sulphur structures appear after removing an excess of sulphur, which mainly desorbs at 358 K as determined from TPD spectra. Furthermore, it was not possible to produce the lower coverage p(4 × 2) sulphur structure by annealing the c(4 × 4) surface. In the case of the p(4 × 2) S overlayer on the Au(1 1 0)-(1 × 2) surface it is proposed that the sulphur is attached to “missing row” sites only. The c(4 × 4) S overlayer arises via desorption of S2 molecules that are formed on the surface due to mobility of sulphur atoms after a prolonged anneal. |
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Keywords: | Au(1 1 0) Sulphur overlayers LEED TPD Auger electron spectroscopy |
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