Laser ablation with
the use of ultra-short laser pulses is a widely
used technique for the fabrication of nanoparticles of metals, inorganic
and hybrid materials. However, fabrication of fragile organic nanocrystals
via
laser ablation is rarely used due to easy photodegradation
of molecules. The method employing laser irradiation of the target
material is beneficial as no other chemicals are used in the production
of nanoparticles, except for a given material and a solvent. In this
work, we test the concept of formation of nonlinear optical (NLO)
organic nanocrystals dispersion in water by irradiation of the microcrystals
of the NLO material with nonabsorbed infrared nanosecond light pulses.
These pulses, due to a nonlinear optical process active in a noncentrosymmetric
organic crystal, such as those studied in this work, DCNP dye (3-(1,1-dicyanoethenyl)-1-phenyl-4,5-dihydro-1
H
-pyrazole), produce nanosecond pulses of second-harmonic
(SH) light. Due to doubling of photon energy, they are reabsorbed
in the volume of DCNP microcrystals and thermal shocks fracture them
into nanometer size crystals. To the best of our knowledge, such process
and its interpretation have not been described yet in the literature.