Head-on Collisions of Xe Atoms Against Superfluid 4 He Nanodroplets

We study the head-on collision of a heliophilic xenon atom with a superfluid 4 He droplet made of 1000 atoms. At variance with the findings for a heliophobic cesium atom of a similar atomic weight, it is found that the xenon atom has to hit the droplet with a large kinetic energy in order to get across it without being captured. When it is not captured, the xenon impurity does not emerge as a bare atom; instead, due to its heliophilic character it carries away some helium atoms.