Nonphotochemical shockwave-induced nucleation and time-resolved anisotropic crystal growth in KNO₃ solutions

We demonstrate shockwave-induced nucleation and crystallization in supersaturated aqueous KNO₃ using a single 7 ns, 532 nm laser pulse on a metallic substrate. The pulse launches shockwaves at low peak power densities (2.18–2.73 GW/cm²), triggering rapid synchronized nucleation. Crystal morphology and changes in length and width were monitored as a function of time. Crystal dimensions increased linearly with time, with enhanced longitudinal growth yielding anisotropic, needle-like morphologies. At fixed power density, longitudinal growth scaled linearly with concentration, whereas lateral growth was suppressed near the spontaneous-crystallization threshold. Nearly constant growth rates indicate interface-limited kinetics and yield narrow, Gaussian-like size distributions.