ISSN:
1089-7690
Source:
AIP Digital Archive
Topics:
Physics
,
Chemistry and Pharmacology
Notes:
In this paper, three distinct phases of biphenyl on the Pd (110) surface are characterized and studied by angle-resolved ultraviolet photoemission (ARUPS); a disordered condensed multilayer which desorbs at 218 K, a bilayer that desorbs at 240 K, and a strongly bound monolayer which breaks up at the surface for temperatures greater than 400 K. The multilayer ultraviolet photoemission (UP) spectrum is almost identical to that of the gas phase spectrum and it is inferred that the torsional angle between the phenyl rings in the condensed phase is unaltered from that in the gas phase. Changes observed in the π orbital emissions on the formation of the bilayer indicate a significant reduction in the torsional angle. Application of the selection rules for ARUPS to the strong angular effects observed in the emissions from the highest-lying π orbitals suggests that the molecules in this second layer have their molecular axes parallel to and molecular planes perpendicular to the surface, that is, edge-on to the molecules in the monolayer which are shown to be flat lying to the metal surface and bonded via the π orbitals.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.458344
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