Rubidium desorption induced by weak and non-resonant light has been ob
served in silane coated cells. The effect is non-thermal and produces
a huge variation of the vapor density at room temperature. This effect
has been observed, for the first time, by Gozzini et al. with sodium
upon similar conditions. The dynamics of this new effect is here discu
ssed and the desorption-adsorption rates are measured.