Photonic bandgap examination in an immersed synthetic opal

We inspected photonic bandgap (stop-zone) in a synthetic opal (photonic crystal) immersed with different liquids. Dependences of the bandgap depth and spectral position on the immersed liquid refractive index were measured in the case of normal light incidence to the (111) face. An explanation of the observed spectral displacement of the bandgap is given on the basis of interaction between forward-propagating wave affected by Bragg diffraction and phase-shifted back-scattered wave.     

Effective acousto-optical interactions in suspensions of nanodiamond particles

We present experimental investigations of interactions of pulsed-laser radiation with colloid suspensions of detonated nanodiamond particles. We register stimulated low-frequency Raman scattering (SLFRS) with high conversion efficiency.     

Preparation of 2-(phenylamino)benzoic acid and 2-[(carboxymethyl)(phenyl)amino]benzoic acid via Ullmann reaction under microwave irradiation

The optimal conditions of preparation of 2-(phenylamino)benzoic acid and 2-[(carboxymethyl)-(phenyl)amino]benzoic acid via Ullmann reaction under microwave irradiation have been determined.     

Stimulated Raman scattering in light and heavy water under picosecond laser excitation

The spectra of stimulated Raman scattering in ordinary and heavy water under excitation by second harmonic of a picosecond Nd:YAG laser were compared. It was shown that when stimulated Raman scattering is excited in water in cavities of a photonic crystal (synthetic opal matrix constructed of silica nanoglobules) or a photonic glass in the form of close-packed monodimensional millimeter-size amorphous-quartz balls, the efficiency of stimulated Raman scattering increases significantly compared to a uniform liquid medium.     

A method for reducing the stimulated Raman scattering threshold in liquids embedded into photonic crystals

We study stimulated Raman scattering (SRS) in liquids (water and ethanol) embedded into photonic crystals (artificial opals) under excitation with 60 ps laser pulses at 532 nm. We observe a substantial decrease of the SRS threshold when the focused laser beam excites the crystals near their surface. The spatial distance between the beam center and the surface of the crystals is close to their nanoscale structure. The decrease in the SRS threshold is due to a substantial increase in the photonic-state density near the edges of the photonic crystal stop zones and the so-called Mie resonances in active media near the nanosized globules. This leads to a considerable increase in the local-electric-field intensity, causing the SRS threshold reduction. Such a method of reducing the SRS threshold opens up a way of creating new efficient laser sources based on photonic crystals and their use for different applications in nanotechnologies.     

Reactivity of 2-diethylaminomethylphenol and its copper(II) complex in the reaction with 4-nitrophenylbis(chloromethyl)-phosphinate

The kinetics of reactions of 2-diethylaminomethylphenol (I) and its Cu²⁺ complex (with a metal: ligand composition of 12) (II) with 4-nitrophenylbis(chloromethyl)-phosphinate have been studied in aqueous-ethanolic media (10–70 vol. % ethanol); bimolecular rate constants have been calculated for the reactions of different forms of compound (I) and complex (II). It was shown that compound (I) in aqueous-ethanolic media is a nucleophilic catalyst for hydrolysis of 4-nitrophenylbis (chloromethyl)-phosphinate. The reactivity of complex (II) is an order of magnitude greater than that of the zwitterion form of the ligand which exists in the same range of pH 7–9.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, pp. 555–560, March, 1991.