  UV continua observed in multi-bubble and single-bubble sonoluminescence
spectra of hydrogen-containing liquids have the same physical nature -
radiative dissociation of electronically excited hydrogen molecules (and
possibly hydrides of heavy rare gases like ArH). In the case of SBSL of "air
bubble in water" the oscillating bubble actually consists of a hydrogen/argon
mixture with periodically changing amount of water vapor. The proposed
mechanism is able to explain all available spectroscopic observations without
any exotic hypothesis but in terms usual for plasma spectroscopy.
