  Numerical solutions of the Enskog-Vlasov (EV) equation are used to determine
the velocity distribution function of atoms spontaneously evaporating into
near-vacuum conditions. It is found that an accurate approximation is provided
by a half-Maxwellian including a drift velocity combined with different
characteristic temperatures for the velocity components normal and parallel to
the liquid-vapor interface. The drift velocity and the temperature anisotropy
reduce as the liquid bulk temperature decreases but persist for relatively low
temperatures corresponding to a vapor behaviour which is only slightly
non-ideal. Deviations from the undrifted isotropic half-Maxwellian are shown to
be consequences of collisions in the liquid-vapor interface which
preferentially backscatter atoms with lower normal-velocity component.
