Sticking probability on metal surfaces: Contribution from electron-hole-pair excitations

Abstract

We use a recently proposed method to calculate the probability $P(E)$ that an incoming particle loses a given energy $E$ to electron-hole-pair excitations. For the case for which an adsorbate level crosses the Fermi energy, we present a simple analytical calculation of the probability $P(E)$ and the sticking probability. For the case for which no such crossing occurs, we give simple estimates and show results of more detailed numerical calculations. For not too heavy adsorbates with levels in the neighborhood of the Fermi energy, we find that the energy loss due to electron-hole-pair excitations should be important. We show that the relative width of $P(E)$ is of the order 1; i.e., the probability for an energy loss $E$ is not sharply peaked around the average energy loss as tacitly assumed in a friction-coefficient approach to sticking.