Femtosecond Laser-Induced Crystallization of 4-(Dimethylamino)-<i>N</i>-methyl-4-stilbazolium Tosylate

Abstract

A femtosecond laser pulse was irradiated to a supersaturated methanol solution of an organic molecule, 4-(dimethylamino)-N-methyl-4-stilbazolium tosylate (DAST), and its efficient crystallization was demonstrated under concentration and temperature conditions where spontaneous crystallization does not occur. The efficiency was higher than that using a nanosecond laser, and the nucleation depended on the laser repetition rate. The results suggest that the nucleation is trigged by cluster formation, which is ascribed to femtosecond laser irradiation effects, such as shock wave generation due to the ablation of the medium and an optical pressure due to the strong electric field.