cause of light bursts in sonoluminescence

When noble gases are "injected" into bubbles in the phenomenon of
sonoluminescence, the light bursts intensify.It is possible that
the noble gas is being heated and made to glow in the walls of the
bubble or inside the bubble itself.But how is the heating occurring -
is it electrical heating from charges passing through the noble gas or
frictional heating from migration of ions?
Assuming that there is a potential difference across the bubble
surface caused by OH - and H + ions (in the case of water for
example) , OH - ions on one hemisphere and H + ions on the other, and
knowing that a bubble is typically 10 ^ - 6 metres across and the
bursts last for about 10 ^ -10 - 10 ^ -11 seconds, we have to conclude
that the hydroxyl ions and protons move towards one another across the
surface of the bubble (to form water molecules) at about 10 ^ 4 - 10 ^
5 m / s (unless we are dealing with slow moving electrons and a net
drift velocity here)These ions typically move in water at only 10 ^ 2
- 10 ^ 3 m/s.
Could they be moving at higher speeds than normal because of the
concentration of energy from sound waves? Or are we dealing with noble
gas heating caused by slow moving electrons? Can anyone offer some
advice on this?

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