  Sonoluminescence occurs when tiny bubbles rilled with noble gas atoms are
driven by a sound wave. Each cycle of the driving field is accompanied by a
collapse phase in which the bubble radius decreases rapidly until a short but
very strong light flash is emitted. The spectrum of the light corresponds to
very high temperatures and hints at the presence of a hot plasma core. While
everyone accepts that the effect is real, the main energy focussing mechanism
is highly controversial. Here we suggest that the heating of the bubble might
be due to a weak but highly inhomogeneous electric field as it occurs during
rapid bubble deformations [A. Kurcz et al. (submitted)]. It is shown that such
a field couples the quantised motion of the atoms to their electronic states,
thereby resulting in very high heating rates.
