This thesis describes an experimental investigation of the photoacoustic effect generated by laser initiated exothermic chemical reactions. Experiments were carried out to determine the influence of the addition of H2O2 on the production of the photoacoustic effect in colloidal suspensions of C nanoparticles in H2O. A Q-switched Nd:YAG laser fundamental at 1064 or its frequency doubled output at 532 nm was used to irradiate the suspensions. A piezoelectric transducer was placed in contact with the cuvette at perpendicular incidence to the direction of propagation of the laser beam to record the acoustic wave. The inclusion of H2O2 in an aqueous C suspension changes the normally endothermic reaction of C with H2O into the highly exothermic reaction of C with H2O2 leading to both an enhanced photoacoustic effect and an increase in light emission from the suspension. Aside from the photoacoutic effect, chemical generation of a sonoluminescing bubble is discussed. The aim of this research is to investigate the possibility of depositing chemical energy into a sonoluminescing bubble, in particular, to determine the influence of the addition of H2O2 on the production of the sonoluminescent light in colloidal suspensions of C nanoparticles in H2O. To generate sonoluminescence, the 1064 nm output of a Q-switched Nd:YAG laser was focused with a lens into a reaction chamber. Light scattering was used to monitor the oscillations in the diameter of the bubble by directing a He-Ne laser beam into the reaction chamber at the point where the Nd:YAG laser beam was focused. Adding hydrogen peroxide to colloidal carbon suspensions increased both the time of the sonoluminescent flash following the laser pulse and the intensity of sonoluminescence, indicating that large, highly energetic gas bubbles were produced. In the last chapter, the application of intense ultrasound to a liquid-gas interface is discussed. The composition of the vapor above an ultrasonic fountain is determined as a function of irradiation time and compared with the results of sparging for five different solutions. The experiments show that ultrasonic distillation produces separations that are somewhat less complete than what is obtained using sparging.
Park, Han Jung,
"Photoacoustic effect and sonoluminescence generated by laser initiated exothermic chemical reactions"
(2011).
Chemistry Theses and Dissertations.
Brown Digital Repository. Brown University Library.
https://doi.org/10.7301/Z0K35RW1
