Analysis of gas bubble formation on light-absorbing microinclusion in liquid during laser irradiation: experimental and theoretical investigation

A simplified theoretical model that describes the formation of a gas bubble on a light-absorbing microinclusion in liquid during laser irradiation is presented. The experimental results of irradiation of agglomerates of carbon black nanoparticles with nanosecond laser pulses in distilled water and aqueous solution of glycerol are obtained. The satisfactory correspondence between the experimental and theoretical results is achieved at low values of the microinclusion light absorptivity and can be associated with additional light scattering caused both by the formation of the gas bubble during the laser pulse action and by the phenomenon of critical opalescence in the superheated liquid. With the increase in the laser fluence against the background of the formation of the small-sized gas bubbles, the large-sized gas bubbles appear, which qualitatively agrees with the dependence of gas bubble size on the laser fluence. In case of multipulse laser irradiation, heat accumulation contributes to more uniform distribution of the gas bubbles’ size. The investigated regularities can be used for optimization of the laser parameters in biomedical and other laser applications.