Fluctuational electromagnetic interaction between a moving particle and a flat surface covered with a thin adsorbed film

The effect of a thin adsorbed film on the fluctuational electromagnetic tangential force of interaction between a moving nanoparticle and a flat solid surface was theoretically studied for the first time in a nonrelativistic approximation. Particular calculations were performed for a metal film on a dielectric and for a dielectric film on a metal. In both cases, the nanoparticle is assumed to be made of a nonmagnetic metal. It is shown that, at a normal temperature, the presence of an adsorbed film may lead to an increase in the tangential friction force by one or two orders of magnitude for a certain relation between the particle distance from the surface and the film thickness. In the case of a dielectric film on a metal substrate, a decrease in the temperature is accompanied by exponential decrease in the viscous friction. For a metal film on a dielectric substrate, the tangential force exhibits a quadratic dependence on the temperature.