Manipulation of adsorbates with electric fields

Various strategies, which lead to the manipulation of molecules adsorbed at surfaces by means of external electric fields are proposed. First, explici tly time-dependent laser radiation is considered. For the example system NH 3-Cu(111), a two-dimensional adiabatic model and nuclear wave packet propag ation are adopted to study the desorption of NH3 by "vibrational ladder cli mbing" and "above threshold desorption," both driven by a series of ultrash ort infrared pulses. Another strategy makes use of static fields and leads to "field desorption," for which isotope effects and higher-order contribut ions to the molecule-field interaction are addressed in some detail. We als o study the reverse process to desorption, adsorption. Starting with (i) th e elastic and inelastic scattering of "randomly oriented" (molecular beam) ammonia molecules off the surface, we then consider (ii) the scattering of static-field aligned molecules and, finally, (iii) the laser-induced adsorp tion (LIA) of gas-phase molecules by stimulated emission of photons. (C) 20 00 American Institute of Physics. [S0021-9606(00)70133-4].