1.2.1.3.2 Laser-induced Nucleation Application of continuous wave42,43 or pulsed lasers44,45 can dramatically shorten induction times in a wide range of solutions. In principle, this provides an intriguing opportunity for accurate spatial and temporal control of nucleation in both batch and continuous systems. Furthermore, laser-induced nucleation can lead to different polymorphs being nucleated compared to identical solutions in the absence of lasers.46
As laser-induced nucleation has been reported for systems which were not significantly absorbing light at the laser wavelengths used, this phenomenon does not necessarily involve photochemical effects.

For pulsed lasers, it has been established that a certain threshold laser power is needed to induce nucleation47,48 and that the probability of nucleation can further increase with increasing laser power. It has been also observed that the probability distribution of induction time in laser irradiated glycine solutions shows bi-exponential distribution, where a certain fraction of samples undergo fast laser-induced nucleation while the rest undergo much slower spontaneous nucleation.
However, the mechanism of laser-induced nucleation in the absence of a photochemical effect is not yet clear. Several mechanisms have been suggested, such as polarization of clusters and cavitation or bubble formation, e.g., caused by heating of nanoparticulate impurities.42–47