Nonphotochemical, Laser-Induced Nucleation of Supersaturated Aqueous Glycine Produces Unexpected γ-Polymorph

Zaccaro, Julien; Matic, Jelena; Myerson, and Allan S.; Garetz, Bruce A.

doi:10.1021/cg0055171

Cited by 213 publications

(245 citation statements)

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“…Finally, another place at which optical force perhaps plays a role is in IR laser photonucleated crystallization of optically transparent molecules in supersaturated solutions (39,40). It was suggested that molecules are orientationally aligned by the GW/cm 2 Nd:YAG laser, as occurs in the Kerr effect.…”

Section: Discussionmentioning

confidence: 99%

Optical forces between metallic particles

Hallock

Redmond²,

Brus³

2005

Proc. Natl. Acad. Sci. U.S.A.

130

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We calculate the optical attractive forces that occur between 30-nm Au or Ag nanocrystals when irradiated at visible wavelengths. These forces show resonances at dipolar plasmon wavelengths, similar to resonances in the near-field electromagnetic intensities. At MW/cm 2 intensities, optical forces can be stronger than van der Waals forces and could be used to organize metallic particles. We also suggest that photonucleation of organic crystals from supersaturated liquid solutions may be caused by optical forces.nanoparticles ͉ photonucleation ͉ bispherical coordinates T his article investigates the possibility that optical forces might be used to organize metallic nanocrystals. It also considers whether optical forces might modify the precise geometry of junctions between metallic nanocrystals. Optical forces derive from the electromagnetic-field intensification that occurs near Ag and Au particles at certain resonance wavelengths. This effect is a local mode of the electromagnetic field: the dipolar surface plasmon. The particle acts as a microscopic antenna, increasing absorption and re-emission of light by nearby molecules and causing the surface-enhanced Raman effect (SERS) (1-5). This enhancement is especially interesting for two particles separated by just a few nanometers. The metallic electron excited-state polarization concentrates at the junction (6), producing a ''hot spot'' of enormous electromagnetic enhancement (7), sufficient to allow the observation of single-molecule Raman spectra (8-10).This article considers the optical forces present between two such closely spaced r ϭ 30-nm metallic particles. The internal electronic polarization in the metal that creates the enhanced local field in the junction also creates force between the particles. This force can be simply understood. Consider two identical particles (or molecules) separated by a distance z. In an electromagnetic field E ៝ , each particle will develop an ac dipole p ៝ ϭ ␣⅐E ៝ oscillating coherently with respect to E ៝ . (In general, such electronic polarization optical dipoles P are the source of Rayleigh scattering, the optical Kerr effect, and trapping of single glass beads in focused laser beams.) Neglecting retardation, the two dipoles are in phase with each other. If the light polarization is along z, then the dipoles are head to tail and the interaction is attractive. With perpendicular polarization, the interaction is repulsive. The dipole-dipole-interaction force scales linearly with the light intensity E 2 and falls off as z Ϫ4 . In the dark, the normal van der Waals force falls off as z Ϫ7 . When the particles are far apart, only the dipole-dipole optical interaction need be considered. When they are separated by a distance of the same magnitude as their size, their mutual polarization is strong, and higher-order moments are important. In this article we consider all separations z for two classical spheres of wavelength-dependent, arbitrary complex dielectric coefficient.A single polarizable particle in a uniform plane-wave fi...

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Section: Discussionmentioning

confidence: 99%

Optical forces between metallic particles

Hallock

Redmond²,

Brus³

2005

Proc. Natl. Acad. Sci. U.S.A.

130

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“…Solutions were transferred to Pyrex test tubes (Corning 99449-13, diameter 13 mm, sample volume 6 cm 3 ) with plastic screw caps lined with rubber inserts. These tubes are similar to those described by Sun et al [21][22][23] Dissolved samples were aged at 25 1C for four days, at the end of which any that had spontaneously nucleated were removed. The dissolution and ageing procedures ensured that there were no unintentional seeds remaining in the samples.…”

Section: Experimental Methodsmentioning

confidence: 96%

Supersaturation dependence of glycine polymorphism using laser-induced nucleation, sonocrystallization and nucleation by mechanical shock

Liu

Berg

Alexander

2017

Phys. Chem. Chem. Phys.

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The nucleation of glycine from aqueous supersaturated solution has been studied using nonphotochemical laser-induced nucleation (NPLIN), ultrasound (sonocrystallization), and mechanical shock of sample vials. It was found that at higher supersaturation, samples were more susceptible to nucleation and produced more of the g-glycine polymorph. The results are described in terms of a mechanism common to all three nucleation methods, involving the induction of cavitation events and pressure shockwaves. The switch in preference from a-to g-glycine was observed to occur over a narrower range of supersaturation values for NPLIN. We attribute this to induction of cavitation events with higher energies, which result in higher localized pressures and supersaturations. Experiments on NPLIN using circularly versus linearly polarized light showed no evidence for binary polarization switching control of glycine polymorphism.

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“…Laser pulses act predominantly on pre-existing molecular clusters by assisting in the organization of pre-nucleating clusters and embryos into nuclei (Figure 2), leading to dramatically increased nucleation rates for supersaturated solutions. It is believed that the plane-polarized light aligns the prenucleating clusters and thereby reduces the entropic barrier to the free energy of activation for critical nucleus formation (Banga et al, 2004;Garetz et al, 1996;Rodríguez-Spong et al, 2004;Zaccaro et al, 2001). This method has not yet been applied to pharmaceuticals, but it should produce similar results as for other organic substances.…”

Section: Laser-induced Crystallizationmentioning

confidence: 99%