Theory of vibrational excitations of adsorbates by the scanning tunneling spectroscopy

A theory to obtain “inelastic” components of electric conductance due to the scattering by adsorbate vibrations is presented. The method is applied to C2H2/Cu(0 0 1) and an interference effect is found through surface localized electronic states which become able to carry current with electron–vibration coupling. A preliminary account for CO/Cu(0 0 1) is also given as well as the relation between the deexcitation rate of vibrational modes due to electron–hole pair excitations and inelastic components of conductance.