Synthesis of 8a-Chlorotetrahydropyrrolo[1,2-H]pyrazine-1,6,7-(2H)-triones from 3-Methylidenepiperazin-2-ones and Oxalyl Chloride

Russian Journal of Organic Chemistry - (Z)-1-Aryl-3-(2-aryl-2-oxoethylidene)piperazin-2-ones react with oxalyl chloride at cooling with the formation of...     

Synthesis of Angular [1,2,5]Oxadiazolo[3,4-b]pyrazino-[1′,2′ : 1,2]pyrrolo[2,3-e][1,4]diazepine by Stepwise Reaction of Pyrrolo[1,2-a]pyrazinetrione with 3,4-Diaminofurazan

Russian Journal of Organic Chemistry - Diaminofurazan reacted with 8-benzoyl-2-phenyl-3,4-dihydropyrrolo[1,2-a]pyrazine-1,6,7(2H)- trione to give addition product of the amino group to the double...     

Raman Scattering in Three-Dimensional Photonic Crystals

The optical properties of three-dimensional photonic crystals associated with the form of reflection spectra from their surface (appearance of a forbidden gap in the energy spectrum) and with the specific features of Raman scattering are analyzed. Idealized models of the energy band structure of photonic crystals are studied. Expressions for the group velocity of photons with energy close to the forbidden gap are derived. Experimental results on the Raman scattering in photonic crystals based on artificial opal as well as in fused silica are discussed. Bands due to quantum-size effects (presence of nanoclusters in fused silica and nanoglobules forming the lattice of globular photonic crystals) were manifested in the spectra of inelastic light scattering. It is proposed to use photonic crystals for the creation of sensitive sensors of organic and inorganic substances using modern Raman techniques.     

Ordering of the structure of hydrogenated silicon films under the influence of laser radiation

A study is reported of the crystallization of amorphous hydrogenated silicon films under the influence continuous radiation from an argon laser. The structure was investigated by Raman scattering of light. The radiation power density during the annealing process was 1.5–4.5 kW/cm² and the exposure was 1/125 sec. The Raman spectra were recorded for power densities below 0.1 kW/cm². The power density threshold for the appearance of crystallites was found to be 3.0 kW/cm². The phonon localization model was used to show that the size of the crystallites produced for power densities of 3 kW/cm² was 40 Å.