Exclusive and Accelerated β-to-α Polymorphic Transition in Glycine Crystals Induced by Femtosecond Laser Pulses

The precise control of polymorphic transitions is of paramount importance in materials science and pharmaceuticals. Here, we report the exclusive and accelerated β-to-α polymorphic transition in glycine crystals induced by tightly focused, high-repetition-rate femtosecond laser pulses. Laser irradiation triggers the transition at the etched area, likely due to molecular reorientation during local melting. Notably, the transition velocity under laser irradiation is several thousand times faster than that observed in spontaneous transitions. Furthermore, we observed that both laser fluence and the crystal’s microenvironment (e.g., dry vs wet) significantly influence the transition dynamics. This study not only provides insights into the mechanism of laser-induced polymorphic transitions but also offers a potential tool for precise polymorph control, which may find broad applications in various materials.