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Site-specific electronic and geometric interface structure of Co-tetraphenyl-porphyrin layers on Ag(111)


Auwarter, W; Seufert, K; Klappenberger, F; Reichert, J; Weber-Bargioni, A; Verdini, A; Cvetko, D; Dell'Angela, M; Floreano, L; Cossaro, A; Bavdek, G; Morgante, A; Seitsonen, A P; Barth, J V (2010). Site-specific electronic and geometric interface structure of Co-tetraphenyl-porphyrin layers on Ag(111). Physical Review. B, Condensed Matter and Materials Physics, 81(24):245403.

Abstract

We present a combined multimethod experimental and theoretical study of the geometric and electronic properties of Co-tetraphenyl-porphyrin (Co-TPP) molecules adsorbed on a Ag(111) surface. Scanning tunneling microscopy (STM) topographs reveal that Co-TPP forms highly regular arrays with a square unit cell. Hereby, the Co-TPP molecules do not occupy a unique adsorption site on the Ag(111) atomic lattice. The central Co atom of the Co-TPP is found to reside predominantly above fcc and hcp hollow sites of the substrate, as determined from the photoelectron diffraction patterns. A strong adsorption-induced deformation of Co-TPP involving a saddle-shaped macrocycle is evidenced by high-resolution STM images and quantified by near-edge x-ray absorption fine-structure measurements. By scanning tunneling spectroscopy we resolved discrete molecular electronic states and mapped the pertaining spatial charge-density distribution. Specifically, we discuss the interaction of orbitals originating from the Co-metal center with the porphyrin macrocycle and show that the varying adsorption sites induce a modulation in the Co-TPP lowest unoccupied molecular orbital. These findings are corroborated by density-functional-theory calculations.

We present a combined multimethod experimental and theoretical study of the geometric and electronic properties of Co-tetraphenyl-porphyrin (Co-TPP) molecules adsorbed on a Ag(111) surface. Scanning tunneling microscopy (STM) topographs reveal that Co-TPP forms highly regular arrays with a square unit cell. Hereby, the Co-TPP molecules do not occupy a unique adsorption site on the Ag(111) atomic lattice. The central Co atom of the Co-TPP is found to reside predominantly above fcc and hcp hollow sites of the substrate, as determined from the photoelectron diffraction patterns. A strong adsorption-induced deformation of Co-TPP involving a saddle-shaped macrocycle is evidenced by high-resolution STM images and quantified by near-edge x-ray absorption fine-structure measurements. By scanning tunneling spectroscopy we resolved discrete molecular electronic states and mapped the pertaining spatial charge-density distribution. Specifically, we discuss the interaction of orbitals originating from the Co-metal center with the porphyrin macrocycle and show that the varying adsorption sites induce a modulation in the Co-TPP lowest unoccupied molecular orbital. These findings are corroborated by density-functional-theory calculations.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:07 Faculty of Science > Department of Chemistry
Dewey Decimal Classification:540 Chemistry
Language:English
Date:2010
Deposited On:23 Dec 2010 10:19
Last Modified:05 Apr 2016 14:15
Publisher:American Physical Society
ISSN:1098-0121
Free access at:Related URL. An embargo period may apply.
Publisher DOI:10.1103/PhysRevB.81.245403
Related URLs:http://www.e20.physik.tu-muenchen.de/Publikationen/Data/PRB_2010-81_245403.pdf
Permanent URL: http://doi.org/10.5167/uzh-36018

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