Adsorption of ethyne on Cu(110): Experimental and theoretical study

High-resolution electron energy loss spectroscopy and angle-resolved ultraviolet photoelectron spectroscopy data indicate that ethyne adopts a low symmetry (most likely C-1) adsorption geometry on Cu(110). Detailed ab initio Hartree-Fock cluster calculations identify a minimum on the potential energy surface for ethyne in a C-1 adsorption geometry. This structure also provides the best agreement between the experimental and calculated vibrational frequencies of the geometries investigated. In addition, the calculations show that the internal structure of the ethyne molecule is relatively insensitive to the adsorption site and that the adsorbed molecule is essentially sp(2) hybridized.