SOME COMMENTS ON THE THERMODYNAMICS OF SONOLUMINESCENCE

The path of the gas in a sonoluminescent bubble must enclose an area i n a P-V plot if the gas itself emits photons. Thermodynamic analysis t hus delineates the playing field that may enable us to distinguish liq uid-phase emissions from gas-phase emissions. The apparent importance of the van der Waals a (which parameterizes mean-square induced dipole attractions) in light intensity supports collision-induced emission a s a likely mechanism. The suggested emitting object, containing 10(10) molecules in picosecond-long van der Waals contact, is novel, being n either plasma, gas, liquid nor blackbody. The bubble pursues a unique thermodynamic path. (C) 1997 Elsevier Science B.V.