Series of He atom angular distributions recorded for clean at a substrate temperature of 70 K along the  high-symmetry direction (top) and for CO adsorbates after the exposure given in the figure (bottom). The incident wave vector of the He beam was and the CO gas was applied at (corrected for ionization probability of 0.95 relative to ).
He atom angular distributions for the clean surface along the high-symmetry direction and for two coverages of CO adsorbates after the exposure given in the figure. The surface temperature was between 74 and 65 K. The incident wave vector of the He beam was and the CO gas was applied at (corrected for ionization probability of 0.95 relative to ).
He-TDS curve, i.e., specular intensity while heating the crystal. The first step at a desorption temperature of 127 K can be attributed to the CO adsorbate. The incident wave vector was .
TDS data of CO (mass 28) for various CO exposures on the perfect surface at 95 K. The inset shows the TD spectrum of CO after exposing the defective surface to 5 L CO at 95 K. The heating rate was 1.5 K/s.
HREELS spectra recorded for the clean surface (curves a and b) and after exposure to 10 L CO at 95 K (curve c). Curve a displays the raw spectrum, and the Fourier-deconvoluted spectra are shown in curves b and c. The spectra were recorded at 95 K in specular direction with an incidence angle of 55° and with a primary energy of 10 eV.
Convergence of the CO adsorption energy with slab thickness at full monolayer coverage. The results for full atomic relaxation with CO adsorbed symmetrically on both sides of the slab are shown by a solid black line. The dashed red line represents the calculations in which CO was adsorbed only on one side of the slab with the bottom two trilayers fixed at the bulk positions and the broken surface bonds at the bottom of the slab saturated with pseudohydrogen atoms.
Fully relaxed atomic structure of a CO monolayer adsorbed on . C, O, and Ti atoms are shown in green, red, and gray, respectively.
Schematic sketch of the orientation of the CO molecules in a monolayer adlayer with (left) a and (right) a periodicity, both containing glide mirror planes.
Comparison of the experimentally observed (open circles) and the simulated (lines) TD spectra for (top) a parameter set of and as taken from the theoretical predictions and a fitted frequency factor of and (bottom) the best fitting parameter set with , , and a frequency factor of .
Results of the periodic DFT/PBE calculations for the adsorption energy (in eV) of CO on and the frequency shift (in ) for the CO stretch mode.
Results for the adsorption energy (in eV) of CO on and the lateral CO–CO repulsion energy (in eV) for CO molecules in a full CO monolayer from embedded cluster Hartree–Fock, MP2, SCS-MP2, and DFT/PBE calculations, and the ZPVC (in eV) evaluated at the DFT/PBE level.
Best estimates obtained from the periodic DFT/PBE and the embedded cluster MP2 calculations for the adsorption energy (in eV) of a single CO molecule adsorbed on .
Best estimates for the lateral repulsion energy (in eV) for a CO molecule in a full CO monolayer (taken with respect to for a single CO and the adsorption energy per CO molecule in a full monolayer).
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