[The light pulses and spectra of straight tube conical bubble sonoluminescence in glycol].

Based on the U-tube, a new type of sonoluminescence apparatus-conical bubble sonoluminescence straight tube apparatus was set up, and the structures and operations were described detailedly. Using the apparatus, the ultrabright cavitation luminescence was obtained in glycol solution. The light pulses of conical bubble sonoluminescence were detected, results show the half width is about 80 micros that is much longer than the results by ultrasound, which should be caused by the fact that the conical bubble can obtain more energy from the flow than the bubbles from the ultrasound. The spectra consist in a broad background ranging from the ultraviolet region to the visible region, on which five clear sequences of Swan bands and three sequences of B 2sigma+ --> X 2sigma+ transition of CN are superimposed. A band assigned to the A 2delta --> X 2II transition of CH was also measured. Specially, the vibrational structures of Swan bands can be resolved. Finally, the achieved molecular vibrational temperature of C2 is estimated to be about (4 200 +/- 200) K.