Nitration of 4-Acetylamino-4'-nitro-, 4-Acetylamino-2'-nitrodiphenyl Sulfides and 4-Acetylamino-2'-nitrodiphenyl Ether

Nitration of 4-acetylamino-4'-nitrodiphenyl sulfide, 4-acetylamino-2'-nitrodiphenyl sulfide, and 4-acetylamino-2'-nitrodiphenyl ether yields respectively 4-acetylamino-3,4'-dinitrodiphenyl sulfide, 4-acetylamino-2',3-dinitrodiphenyl sulfide, and 4-acetylamino-2',3-dinitrodiphenyl ether.     

Condensed Tetrazolo-1,3,5-triazines. 1. Synthesis of 5-Polynitromethyltetrazolo[1,5-<Emphasis Type="Italic">a</Emphasis>]-1,3,5-triazin-7-one Salts

The aziridation of 2-R-4,6-bis(trinitromethyl)-1,3,5-triazines containing electron-donor substituents has been studied. It was found that the corresponding 4-azido-2-dialkylamino-6-trinitromethyl-1,3,5-triazines are formed when R = NMe₂, NEt₂. When R = O^–NMe₄ ⁺ a novel reaction route was discovered leading to the tetramethylammonium salt of 5-polynitromethyltetrazolo[1,5-a]-1,3,5-triazin-7-one which is formed as a result of azido-tetrazole and lactim-lactam tautomeric conversion. Denitration of this salt at the trinitromethyl group occurs with retention of the tetrazolo-1,3,5-triazine structure. An X-ray analysis was carried out for the denitration product which was the dipotassium salt of 5-dinitromethyltetrazolo[1,5-a]-1,3,5-triazin-7-one.__________Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 259–266, February, 2005.     

Array of femtosecond plasma channels in fused silica

We have shown experimentally and confirmed by means of full dimensional (3D + 1) numerical simulations, the possibility to create an array of refractive index modification zones inside a fused silica sample using a 43 fs, 2 mJ, 800 nm laser pulse and a periodic mesh introduced in front of the sample. Robust filaments and the corresponding refractive index modification zones preserve their transverse positions for more than 10 Rayleigh lengths (∼500 μm). Numerical simulations prove that each mesh unit is an independent source of the background energy for a filament formed within this unit. The effect of the simultaneous formation of many extended periodically spaced filaments can be used to accelerate the fabrication of microoptics devices.     

Conical emission from laser plasma interactions in the filamentation of powerful ultrashort laser pulses in air

We performed detailed experimental and numerical investigations of the conical emission (CE) accompanying the filamentation of powerful ultrashort laser pulses in air. It was found that the CE originates from self-phase modulation in the plasma produced by the pulse during propagation. The experiment and the simulation agree on the essential features of the CE: The CE angle decreases with increasing wavelength and is independent of the position along the filament, and there is no CE at Stokes-shifted wavelengths.     

Radiation-Chemical Aspects of Radioactive Waste Management

Studies of radiation-chemical processes in model liquid radioactive waste are summarized. These processes are radiolytic transformations of various substances present in the waste (actinide ions (primarily, neptunium and plutonium ions), inorganic matter (for example, nitrate ions), and organic compounds (acetic acid, EDTA, etc.)) and radiolytic gas evolution. Attention was focused on the latter process. The volumes and compositions of gases formed in the -radiolysis of aqueous solutions that simulated intermediate-level and high-level liquid waste were determined. It was found that the nature and the radiation-chemical yields of released gases depend on the absorbed dose, the composition and concentration of solutions, the irradiation temperature, the presence of solid substances, etc. In a number of cases, data obtained with model solutions were compared to the results of studies of real liquid radioactive waste.     

Breaking of the Axial Symmetry of Terahertz Radiation from Single-Color Filament Plasma

JETP Letters - Two-dimensional distribution patterns of terahertz radiation generated in a laser single-color filament plasma are measured at several frequencies. In the low-frequency region...     

Optimum small-scale management of random beam perturbations in a femtosecond laser pulse

The geometric phase of a three-level atom interacting with single-mode in the presence of the one-dimensional photonic band gap material is studied. We consider dipole emitters situated in the thin slab region between two semi-infinite one-dimensionally periodic photonic crystals, a situation reminiscent of planar cavity laser structures. It shows that the Pancharatnam phase depends crucially on the presence of the photonic band gap. This feature is attributed to the fact that in the photonic band gap region electromagnetic modes are not allowed to propagate into the dielectric slab and hence no interaction can take place in this region. The outcomes are illustrated with numerical simulations applied to GaAs. PACS 03.67.-a; 32.80.Pj; 42.50.Ct; 42.65.Yj; 03.75.-b     

What is a filament?

By using intensity clamping as a guideline for the definition of a filament, we propose that a filament is the propagation core where plasma is generated.