CuPc molecules adsorbed on Au(110)-(1x2): growth morphology and evolution of valence band states

TL;DR

This study investigates how copper phthalocyanine molecules grow and interact electronically on a reconstructed gold surface, revealing changes in surface and molecular states with increasing coverage.

Contribution

It provides detailed insights into the growth morphology, surface reconstruction effects, and valence band evolution of CuPc on Au(110)-(1x2), combining LEED and HR-UPS techniques.

Findings

LEED patterns show (5x3) reconstruction during early adsorption

Surface states disappear as molecules cover the surface

Molecular HOMO emerges in the valence band with increased coverage

Abstract

We present the growth morphology, the long range ordering, and the evolution of the valence band electronic states of ultra-thin films of copper phthalocyanine (CuPc) deposited on the Au(110)-(1x2) reconstructed surface, as a function of the organic molecule coverage. The Low Energy Electron Diffraction (LEED) patterns present a (5x3) reconstruction from the early adsorption stages. High-Resolution UV photoelectron spectroscopy (HR-UPS) data show the disappearance of the Au surface states related to the (1x2) reconstruction, and the presence of new electronic features related to the molecule-substrate interaction and to the CuPc molecular states. The CuPc highest occupied molecular orbital (HOMO) gradually emerges in the valence band, while the interface electronic states are quenched, upon increasing the coverage.