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

1.2.1.3.3 Effects of Electric or Magnetic Fields on Nucleation A theoretical description of the effect of an electric field on the homogeneous nucleation rate preceded experimental work and concluded that depending on the ratio of dielectric constants between solution and solid the nucleation rate will decrease or increase.49 One of the first experimental reports on the combination of electric field and crystallization showed that the electric field enabled the crystallization of an enzyme.50 Later on, it was shown that crystals of lysozyme formed with a preferred orientation on the electrode, probably because of the field's influence on the nucleation process.51