Adsorption dynamics of cold atoms: Decay of surface Feshbach resonances

The adsorption of a cold atom to a surface has been described by Clougherty and Kohn in terms of the decay of overlapping Feshbach resonances involving the incident atom channel with the adsorbed atom accompanied by excitations of the solid. Since this resonance condition can be tuned with applied stress, adsorption on a 2D material might be controlled by tension. The dynamics of adsorption of cold atoms on 2D materials is studied theoretically using the Dirac-Frenkel time-dependent variational principle with a trial state consisting of a time-dependent linear combination of the incident atom and a bound atom with single-phonon-added coherent states. The effect of tension on the adsorption rate is the principal focus of this study. Tensile stress (1) reduces the strength of atom-surface potential at long distances, consequently tuning the scattering length; and (2) increases the transverse speed of sound in the 2D material, decreasing the phonon density of states. Both of these effects will alter the adsorption rate. Thus, applied tensile stress might in principle be used to control cold atom adsorption on 2D materials.