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Reaction of CO with gold atoms and clusters on TiO2(110)

PhD Studentship Available (to start October 2012)

Scanning Tunnelling Microscocpy (STM) has revolutionised our understanding of surfaces by providing real space images with atomic resolution, while playing the dual role of manipulation tool and imaging device. Until recently, the technique lacked chemical specificity, requiring complementary spectroscopic tools such as FTIR, HREELS or photoemission to identify the species being imaged. However, in the past few years scanning tunneling spectroscopy (STS) and STM– IETS (STM Inelastic Electron Tunnelling Spectrscopy) have been developed as a powerful tool in the chemical analysis of single molecules and their reactions [1,2]. By recording the changes of conductance due to single-mode vibrational excitation, STM–IETS is capable of mapping the excitation of modes in real space with sub-Å spatial resolution and meV spectral resolution. In other words, STM-IETS can be used to measure the vibrational spectrum of a single molecule. For instance, our results for N2 on Cu(110) at 4 K show losses consistent with molecules at defect sites being chemisorbed, with those at regular lattice sites being physisorbed [3]. In this project STS and STM-IETS will be used to understand the very high efficiency of CO oxidation catalysis of Au on TiO2 [4]. This will involve first monitoring the variation of electronic structure with Au cluster size, starting with single gold atoms. The second set of experiments will examine the bonding of CO to the gold clusters, again using STS. This would be carried out in year one of the studentship. Year two would be spent in Lyon carrying out density functional calculations with a hybrid functional basis to interpret the experimental data. In year three, back in London STM-IETS measurements of the vibrational spectra would be used to explore the strength of bonding of CO to Au using the CO stretch frequency. The variation with bonding site and cluster size will be examined. 

The studentship is for three years with a tax-free stipend of GBP 14500. The fees are paid. 

The student will receive a joint PhD degree from UCL and ENS-Lyon. 

[1] H.J. Lee and W. Ho, Science 286 (1999) 1719. 

[2] A.C. Papageorgiou, N.S. Beglitis, C.L. Pang, G. Teobaldi, G. Cabailh, Q. Chen, A.J. Fisher, W.A. Hofer, G. Thornton, Proc. Nat. Acad. Sci. USA, 107 (2010) 2391 

[3] L. Leung, C.A. Muryn, G. Thornton, Surf. Sci. 566–568 (2004) 671 

[4] M. Haruta et al, J Catalysis 144 (1993) 175

Please contact Prof. G. Thornton for more information at g.thornton[at]ucl.ac.uk