Experimental evidence for methoxide geometry on clean Ru(0 0 1)

Clean Ru(0 0 1) was exposed to an extremely low dose of CHD2OH (∼0.01 L) at 90 K, and the geometry of adsorbed methoxide-d2 characterized by reflection–absorption infrared spectroscopy (RAIRS). It is conclusively demonstrated that this species adsorbs in an upright geometry (pseudo-C3v local symmetry). It is the first time that such experimental evidence is obtained on this surface. The consistency with the configuration predicted by DFT cluster calculations for isolated methoxide on Ru(0 0 1) allows inferring that only at such extremely low coverages this species adsorbs on three-fold hcp hollow sites, in an upright geometry. The coverage effect is pointed out by exposing the surface to a higher dose of CHD2OH at 90 K (0.1 L), which is already enough to induce the tilting of CHD2O–, probably associated with adsorption on less stable sites.