Adsorbate hopping via vibrational-mode coupling induced by femtosecond laser pulses

We study the heat transfer from femtosecond laser-heated hot electrons in a metal to adsorbates in the presence of vibrational-mode coupling. The theory is successfully applied to the experimental result of atomic oxygen hopping on a vicinal Pt(111) surface. The effective friction coupling between hot electrons and the vibrational mode relevant to the hopping motion depends on the transient temperature of the partner mode excited by hot electrons. The calculated two-pulse correlation and fluence dependence of the hopping probability reproduce the experimental results, which were previously analyzed using the hot-electron temperature (Te)-dependent friction eta(a)(Te) in a conventional heat transfer equation. A possible elementary process behind such a hypothetic modeling using eta(a)(Te) is discussed in terms of an indirect heating of the vibrational mode for hopping at the surface