Laser-Induced Explosive Vaporization of Liquids in Contact with a Solid Surface: Fundamental Studies and Applications

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ABSTRACT -- CTS-9317708 Grigoropoulos This proposal is concerned with novel science and important technological applications of the phenomenon of rapid nucleation and explosive vaporization of a liquid film in contact with a pulsed laser-heated surface. The science of the metastability behavior of superheated liquids is well established only in the near-steady-state regime at the millisecond time scale. In the much faster regime with a nanosecond time scale, superheated liquids may have different behavior, with regard to the possible superheating, bubble nucleation and growth kinetics, and the inhomogeneous nucleation process at a surface. Such behaviors in the fast regime have not been investigated until one recent study because traditional experimental techniques lack the speed and sensitivity. A recent study by the PI provides preliminary results on the nucleation and growth of bubbles in various liquids in contact with a pulse-laser-heated solid surface using a new simultaneous reflectance/scattering monitoring approach. Further quantitative experimentation and modeling are necessary for understanding the phase change phenomena involved. Significant applications of these pulse liquid film explosive vaporization phenomena in industry are possible. Practical implementation will be pursued with the goal of demonstrating manufacturing yield and productivity in a high-technology production environment. The first application is in the area of "laser cleaning" to remove micron and sub-micron particles from critical parts of modern electronic and data-storage devices. Other applications to be investigated include photo-acoustic pulse generation for nondestructive evaluation, enhanced laser-micromachining, and novel patterned-doping of surfaces.