Single Pulse, Single Crystal Laser-Induced Nucleation of Potassium Chloride

The nonphotochemical laser-induced nucleation of aqueous supersaturated solutions of potassium chloride is demonstrated. We have observed that a single, 7 ns pulse of near-infrared (1064 nm) laser light can be used to grow a single crystal of potassium chloride. The experimental results are analyzed using a model in which nucleation is enhanced through the isotropic electronic polarization of subcritical crystal nuclei by laser radiation and the associated reduction in free energy of the nuclei. Classical nucleation theory is used to calculate the fraction of subcritical nuclei, initially in zero field, which become supercritical in the laser field; this fraction is correlated with the crystallization yield and is shown to successfully describe the dependences of the experimentally observed yields upon laser power and supersaturation. The experimental results are analyzed to obtain a phenomenological value of the crystal-solution interfacial tension, gamma = 2.19 +/- 0.03 mJ m(-2).