Coverage-dependent molecular tilt of carbon monoxide chemisorbed on Pt{110}: A combined LEED and DFT structural analysis

Abstract

The adsorption of carbon monoxide on the Pt{110} surface at coverages of 0.5 ML and 1.0 ML was investigated using quantitative low-energy electron diffraction (LEED IV) and density-functional theory (DFT). At 0.5 ML CO lifts the reconstruction of the clean surface but does not form an ordered overlayer. At the saturation coverage, 1.0 ML, a wellordered p(2 × 1) superstructure with glide line symmetry is formed. It was confirmed that the CO molecules adsorb on top of the Pt atoms in the top-most substrate layer with the molecular axes tilted by ±22 • with respect to the surface normal in alternating directions away from the close packed rows of Pt atoms. This is accompanied by significant lateral shifts of 0.55Å away from the atop sites in the same direction as the tilt. The top-most substrate layer relaxes inwards by -4 % with respect to the bulk-terminated atom positions, while the consecutive layers only show minor relaxations. Despite the lack of long-range order in the 0.5 ML CO layer it was possible to determine key structural parameters by LEED IV using only the intensities of the integer-order spots. At this coverage CO also adsorbs on atop sites with the molecular axis closer to the surface normal (< 10 • ). The average substrate relaxations in each layer are similar for both coverages and consistent with DFT calculations performed for a variety of ordered structures with coverages of 1.0 ML and 0.5 ML.

A DFT Structural Investigation of New Bimetallic PtSnx Surface Alloys Formed on the Pt(110) Surface and Their Interaction with Carbon Monoxide

“…The most stable adsorption sites and CO adsorption energies were evaluated using this approach. For the pure Pt(110) surface, the preferred site for CO adsorption is at the top position (hereafter indicated as O), with an adsorption energy of −1.80 eV, which is comparable with the results reported by other groups (∼2.2 eV) but quantitatively different, the reason being the different settings and codes used for the calculations. − …”

Infrared spectroscopy data- and physics-driven machine learning for characterizing surface microstructure of complex materials

“…To incorporate high coverage ordered overlayers into the GCN pdf model, firstprinciples data also includes the (111), (100), and (110) extended surfaces of Pt with adsorbed CO overlayers that correspond to the highest coverage pattern determined experimentally by LEED. For these facets, the highest coverage overlayers are the c(4 × 2) 2 , c(4 × 2) 41 , and p(2 × 1) 60 configurations, respectively, that correspond coverages of 0.5, 0.75, and 1 ML, as discussed extensively in literature 44 .…”

Adsorption structure determination of a large polyaromatic trithiolate on Cu(111): combination of LEED-I(V) and DFT-vdW

“…6 Here the intensities of unique reflections in a LEED experiment are recorded as a function of electron energy. A prerequisite for this diffraction technique is the availability of long-range ordered monolayers, and owing to the elaborate nature of the scattering simulations application of the technique was hitherto restricted to smaller, conformationally rigid adsorbates like dinitrogen, 7 carbon monoxide, 8 formic acid, 9 cyanide, 10 glycine, 11 thiouracil, 12 benzyne, 13 or benzene. [14][15][16][17][18][19] LEED-I(V) analyses of larger adsorbates to date have been rare, examples being studies on graphene 20 and C 60 fullerenes.…”