Temporal dynamics of crystallization initiated by single laser pulse irradiation

In this study, single-shot laser-induced crystallization was employed to trigger nucleation and accelerate crystal growth in supersaturated KNO₃ solutions. Time-resolved observations of crystallization, initiated by 7-ns, 532-nm laser pulses at peak power densities of 85.7–107 GW cm⁻², are presented. A theoretical framework for single-pulse nucleation and early crystal growth in metastable solutions is also developed to interpret the observed dynamics. Post-growth analysis of harvested crystals was performed to monitor the evolution of crystal size, morphology, and size distribution over time scales ranging from seconds to a few minutes. This short timescale, relative to spontaneous crystallization, allows for single-shot crystallization studies that are unaffected by spontaneous nucleation. Average crystal dimensions were found to increase linearly with laser power density, with longitudinal growth rates exceeding lateral growth, which resulted in the production of needle-like crystals. Smaller, slower-growing crystals were produced by lower-intensity pulse irradiation. Longitudinal growth rates were observed to rise linearly with solution concentration, while lateral growth peaked at S = 1.2 and declined at S = 1.3, indicating the dominance of longitudinal growth at higher concentrations nearing the threshold for spontaneous crystallization initiation. Crystal size distributions were narrow and well-described by Gaussian fits, suggesting temporally synchronized nucleation and a uniform growth environment.