Face-Dependent Bond Lengths in Molecular Chemisorption: The Formate Species on Cu(111) and Cu(110)

Many previous structural studies of molecular adsorbates on metal surfaces indicate that the local coordination and bonding is closely similar to that in organometallic compounds, implying that the metallic substrate has no significant influence. Here we show that such an influence is detectable for one model system, namely, the formate species, HCOO, adsorbed on the atomically rough and smooth (110) and (111) surfaces of Cu, leading to a statistically significant difference ($0.09\pm 0.05\AA$) in the Cu-O chemisorption bond length. The effect is reproduced in density functional theory calculations.

Figure 1

Schematic diagrams of the local adsorption structure of the formate species on Cu(110) and Cu(111) as determined in this study.

Figure 2

Comparison of the experimental O $1s$ PhD modulations spectra, recorded in several different emission directions (polar angle and azimuth) from the adsorbed formate species on Cu(110) and Cu(111), with the results of multiple-scattering simulations for the best-fit structures.