Chemisorption-induced gap state at organic-metal interface: Benzenethiol on Pt(111).
Electron emission spectra obtained by thermal collisions of He*(2(3)S) metastable atoms with benzenethiol (C(6)H(5)SH) on Pt(111) were measured to characterize the chemisorption-induced gap state (CIGS) formed at the organic-metal interface. First-principles calculations using density functional theory were also performed for an ordered thiolate (C(6)H(5)S) monolayer on Pt(111). Our data exhibit that the CIGS due to the S 3p-Pt 5d mixings appears just below the Fermi level (E(F)) of the substrate, where the local density of states decreases drastically from the S terminal to the benzene ring. Furthermore, strong benzene pi(1e(1g))-S 3p couplings are apparently lifted upon the formation of thiolate. These features indicate that thiolate is not a good mediator of metal wave functions at E(F), which is closely related to tunneling probability (and eventually electric conductance) in the relevant metal-organic-metal junctions at zero bias.
Masuda
Shigeru
S
Department of Basic Science, Graduate School of Arts and Sciences, The University of Tokyo, Komaba, Meguro, Tokyo 153-8902, Japan. masuda@piesap.c.u-tokyo.ac.jp
Kamada
Toyohiro
T
Sasaki
Keita
K
Aokia
Masaru
M
Morikawa
Yoshitada
Y