A study was made of the adsorption of acetylene on Cu(110) by means of low-temperature scanning tunnelling microscopy. Adsorbed molecules preferentially aggregated at 40K to yield dimer, trimer and larger islands on the surface. Isolated species (monomer) adsorbed on the four-fold hollow site with approximately sp3 rehybridization as characterized by inelastic electron tunnelling spectroscopy. The tunnelling electron induced an acetylene molecule to migrate along the trough of Cu(110). The migration proceeded in 2 steps. Firstly, the molecule hopped to the adjacent long-bridge site and then to the next four-fold site. The voltage and current dependences of the hopping probability showed that the migration was induced by inelastic electron tunnelling that caused vibrational excitation mainly of the C-H stretching mode.

Adsorbed States and Scanning Tunneling Microscopy Induced Migration of Acetylene on Cu(110). T.Kumagai, S.Hatta, H.Okuyama, T.Aruga: . Journal of Chemical Physics, 2007, 126[23], 234708