Behavior of Thermally Induced Nanobubbles during Instantaneous Particle Heating by Pulsed Laser Melting in Liquid

Pulsed laser melting in liquid (PLML) is a technique to produce submicrometer spherical particles (SMPs). In this process, raw particles dispersed in liquid are selectively heated, and thermally induced nanobubbles (TINBs) at the particle surface are generated and act as a thermal barrier to enhance the temperature increase during heating. However, monitoring TINBs is difficult since PLML is a low-temperature, nonplasma process. Simple transmittance measurements of monodisperse Au SMP (250 nm) colloidal solutions on a transient time scale were used to monitor the temporal dependence of the TINB thickness and the pressure within the bubble. By applying this technique for ZnO and Sn SMP formation, TINBs in the PLML process are important in promoting the formation of large particles via particle merging during laser heating.