Non-photochemical laser-induced nucleation

Non-photochemical laser-induced nucleation (NPLIN) is the formation of a new phase from a metastable phase by the action of light on matter. Using millijoule, nanosecond laser pulses at visible and near-infrared wavelengths, it is possible to form the new phase localized in the volume of the beam. In the case of nucleating molecular solids, the laser polarization may have an effect on the particular polymorph that is formed. Despite the huge potential for applications of NPLIN, there is uncertainty regarding the molecular-scale mechanism, and various possible scenarios may well be relevant to nucleation in general and not just NPLIN. In this Perspective, the discovery and phenomenology of NPLIN are described, putative mechanisms are outlined, and some observations on the broader class of nucleation phenomena are given. © 2019 Author(s).The authors acknowledge support from the Engineering and Physical Sciences Research Council (EPSRC) through funding for some of the work described in this Perspective (Nos. EP/G067546/1, EP/I033459/1, and EP/L022397/1). P.J.C. acknowledges support from the Ministry of Education and Science of the Russian Federation (Agreement No. 02.A03.21.0006 and Project No. 3.1438.2017/4.6). We are grateful to our colleagues, collaborators, reviewers, and editors for their encouragement and suggestions over the years