Organic Nanocrystal Fabrication Using the Process of Resonant Second-Harmonic Generation of Light

Abstract

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.

Polarization-dependent second harmonic generation in peptide crystals: effects of molecular packing

“…The SHG efficiency of these peptide microcrystals is comparable to that of inorganic BBO crystals for the 700–900 nm wavelength band. 30 The differences in the substituent sidechains are not reflected in the linear optical absorption and PL spectra – which are very similar for all three samples. However, as SHG is sensitive to the molecular packing and crystal symmetry, a polarization-dependent study of SHG from the bulk crystals of these peptide samples shows the effects of the molecular distribution and crystal packing in the unit cells.…”

“…[20][21][22][23][24][25][26][27][28] However, to develop a bulk SHG material, the molecular building blocks must also be packed into a non-centrosymmetric crystal structure. [29][30][31][32] Rosenne and co-workers reported strong SHG in monosubstituted perylenediimide nanocrystals. 33 Rowan and co-workers studied the self-assembly of a V-shaped fluorenone-based intramolecular charge transfer material into a unique noncentrosymmetric microfibre structure with a permanent dipole along the long axis of the fibre and a transition dipole perpendicular to it.…”

“…20–28 However, to develop a bulk SHG material, the molecular building blocks must also be packed into a non-centrosymmetric crystal structure. 29–32…”

Tale of a Growth: Marangoni Bursting Phenomenon as a Viable Route for Obtaining Fibers of Organic Chromophores

“…4 Recently, the photofragmentation of micrometer-size DCNP crystallites has been demonstrated using the resonant SHG process with Nd 3+ :YAG laser (λ = 1064 nm) as an excitation source. 14 Short (10 ns) thermal stresses due to reabsorption of the generated 532 nm light in the microcrystal volume lead to their fragmentation into nanocrystals. Nanocrystals of DCNP dispersed in water remain to show SHG light, but their luminescence is strongly attenuated.…”

SDS‐capped 1‐pyrenecarboxaldehyde nanoprobe for selective detection of Cu2+ ion from water samples: Spectroscopic approach

“…It is also possible to make molecules to aggregate differently to produce aggregation-induced enhanced emission (AIEE) of wavelengths that are different than its excimer emission. FONPs have been prepared using laser ablation [31], emulsification diffusion [32], and reprecipitation methods [31,33]. Among these, reprecipitation methods have been widely applied to synthesize of FONPs because of their simplicity and low cost, as water is the major solvent required in the process.…”