Abstract
The interaction of oxalic acid with the Cu(110) surface has been investigated by a combination of scanning tunnelling microscopy (STM), low energy electron diffraction (LEED), soft X-ray photoelectron spectroscopy (SXPS), near-edge X-ray absorption fine structure (NEXAFS) and scanned-energy mode photoelectron diffraction (PhD), and density functional theory (DFT). O 1s SXPS and O K-edge NEXAFS show that at high coverages a singly deprotonated monooxalate is formed with its molecular plane perpendicular to the surface and lying in the [11¯0] azimuth, while at low coverage a doubly-deprotonated dioxalate is formed with its molecular plane parallel to the surface. STM, LEED and SXPS show the dioxalate to form a (3 × 2) ordered phase with a coverage of 1/6 ML. O 1s PhD modulation spectra for the monooxalate phase are found to be simulated by a geometry in which the carboxylate O atoms occupy near-atop sites on nearest-neighbour surface Cu atoms in [11¯0] rows, with a Cu–O bondlength of 2.00 ± 0.04 Å. STM images of the (3 × 2) phase show some centred molecules attributed to adsorption on second-layer Cu atoms below missing [001] rows of surface Cu atoms, while DFT calculations show adsorption on a (3 × 2) missing row surface (with every third [001] Cu surface row removed) is favoured over adsorption on the unreconstructed surface. O 1s PhD data from dioxalate is best fitted by a structure similar to that found by DFT to have the lowest energy, although there are some significant differences in intramolecular bondlengths.
Original language | English |
---|---|
Pages (from-to) | 134-143 |
Number of pages | 10 |
Journal | Surface Science |
Volume | 668 |
DOIs | |
Publication status | Published - Feb 2018 |
Bibliographical note
Funding Information:The authors thank Diamond Light Source for access to beamline I09 (proposal number SI8436) that contributed to the results presented here. DAD would like to acknowledge funding from the Alexander von Humboldt Foundation . S.F. acknowledges the CINECA Award N.HP10CJCRO0, 2011 for the availability of high performance computing resources and support. G.C. acknowledges financial support from the EU through the European Research Council (ERC) Grant “ VISUAL-MS ” and from the EPSRC ( EP/G043647/1 ).
Publisher Copyright:
© 2017 The Authors
ASJC Scopus subject areas
- Condensed Matter Physics
- Surfaces and Interfaces
- Surfaces, Coatings and Films
- Materials Chemistry