Metastable-phase crystallization of potassium acetate triggered by focused irradiation with ultrashort laser pulses

The preparation of desired crystal polymorphs has significant implications for designing materials with tailored properties; however, conventional methods often face limitations in terms of precision and reproduction. In this study, we demonstrate the crystallization of a metastable phase of potassium acetate by ultrashort laser ablation of supersaturated aqueous solutions. By varying the laser energy (0.1-300 μJ per pulse) and pulse duration (0.1-10 ps), we found that shorter laser pulses could induce metastable-phase crystallization with lower pulse energy. We also systematically investigated cavitation bubble generation, which is a possible perturbation of crystallization, revealing that shorter laser pulses can provide a higher crystallization probability even with smaller cavitation bubbles. Our results suggest that the precise regulation of positive (e.g., cavitation bubble generation) and negative effects (e.g., temperature elevation) is crucial for the induction of metastable-phase crystallization, which has potential applications in pharmaceuticals, advanced materials, and chemical engineering.