Temperature-dependent coupling of low frequency adsorbate vibrations to metal substrate electrons

The vibrational response of CO on Cu(111) is examined following femtosecond visible pulse excitation of the substrate. We consider the effects of excitation pulse fluence on vibrational energy transfer between the CO low frequency frustrated translation and metal substrate electrons. The temperature dependent coupling rate is extracted from our data using a dynamical charge transfer model, A zero temperature coupling rate of gamma(e)(0) = 25(+/-7) GHz (tau(e)(0) = 40(+/-8) ps) is found to account for the energy transfer between the substrate electrons and the frustrated translation vibration.