Properties of luminescence from laser-created bubbles in pressurized water.

The properties of the luminescence pulse from collapsing laser-created bubbles in pressurized water are studied for pressures between 0.25 and 15 bars. The duration of the light pulse is found to be linear in the maximum bubble size, but for a given bubble size it increases with the applied pressure p as p0.38. The number of photons emitted increases quadratically with the bubble size, and increases approximately linearly with pressure. The spectrum of the luminescence is blackbody in form, with a temperature that increases somewhat with pressure, from 8100 K at 1 bar to 9400 K at 10 bars. At higher pressures the blackbody temperature drops, but this is primarily due to the rapid onset above 10 bars of a fission instability, where the bubbles split into two just before the collapse point.