Mechanoluminescence induced by acoustic cavitation

When a liq. is irradiated with high intensity ultrasound, micron-sized bubbles can be driven into violent collapse with a subsequent shockwave formed in the liq. from the bubble rebound. Small particles suspended in ultrasonically irradiated liqs. can be accelerated to high velocities (several hundred m/s) by these shockwaves and undergo violent interparticle collisions. Under these conditions we have obsd. intense mechanoluminescence from a variety of org. microcryst. solids. We have studied the effects of liq. properties as well as crystal properties to obtain the most intense mechanoluminescence. Using optical emission spectroscopy of at. and mol. species we have characterized the electron d., electron temp., pressure, and temp. of the resulting discharge.