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Department of Physics & Astronomy

Correlation between surface electronic structures and chemical properties of Pt and Pt-alloys

2019-08-29l 조회수 1017
일시 : 2019-11-20 16:00 ~
연사 : Prof. Mun, Bongjin Simon (GIST)
담당 : Prof. Hongki Min., Prof. Bohm Jung Yang, Prof. Dohun Kim
장소 : Bldg.56, Rm 106
In this presentation, with high-resolution state-of-art angle-resolved photoemission (ARPES) and one-step model of photoemission calculations, the direct visualization of occupied covalent bonding states will be delivered for the system of CO molecules on Pt and Pt-alloy surface. From our ARPES results on Pt(111) and Pt-Sn/Pt(111) 2x2 surface alloy, the occupied covalent bonding states, i.e. the overlap of 2 p orbital of CO molecule with the electronic bands of substrates, are directly observed as the spectral features of ARPES near Fermi level. The feature of orbital overlap can be understood as the formation of back-donation state from the substrates to CO molecules in the classic picture of Blyholder model. As surface coverage of CO increases, the overlap, i.e. the strength of covalent bonding, increases accordingly. Furthermore, compared to Pt(111) surface, the amount of back-donation charge from Pt-Sn/Pt(111) 2x2 surface is reduced almost by half, which explains the weak bonding of CO on Pt-Sn/Pt(111) 2x2 surface alloy.
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