We consider here the process of normal boiling as induced by laser-pulse or
ion bombardment. Normal boiling (thenceforth "boiling") refers to the appe
arance of heterogeneously nucleated bubbles which diffuse towards the outer
surface of a liquid and, if the surface is reached, may possibly escape. W
e will here present evidence that boiling, whether the distance scale is at
omically small (5-15 nm, as for laser-pulse or ion impact on a metal in the
absence of thermal diffusion) or much larger, has a prohibitive kinetic ob
stacle because it requires bubble diffusion. That is to say: boiling will n
ever be a significant process for bombardment with laser pulses which are s
hort (< 1 mu s) or with ions in general. This leaves vaporization and phase
explosion as the only possible thermal-spike processes capable of expellin
g material from a laser-pulse or ion bombarded surface in a significant qua
ntity. (C) 2000 American Institute of Physics. [S0021-8979(00)03006-1].