Synthesis of N-Vinylpyrrolidone-Vinyltrimethoxysilane Copolymers

N-Vinylpyrrolidone-vinyltrimethoxysilane copolymers were prepared by radical copolymerization. The composition of the copolymer was studied in relation to the reaction temperature and composition of the initial mixture. The kinetic parameters of the monomer activity were calculated.     

Synthesis and crystal structure of bis(carbamide)chromatoneptunyl NpO2CrO4 · 2[OC(NH2)2]

The crystal structure of the hexavalent neptunium complex NpO₂CrO₄ · 2[OC(NH₂)₂] is determined. The crystal data are a = 7.192(2) Å, b = 12.902(4) Å, c = 11.226(3) Å, β = 92.19(2)°, V = 1040.9(4) ų, space group P2₁/n, Z = 4, d _calcd = 3.223 g/cm³, R = 0.045, and R _w = 0.130. The coordination polyhedron of the Np atom is the pentagonal bipyramid whose equatorial plane is formed by the oxygen atoms of the chromate ions and carbamide molecules.     

Frequency-lock system for microwave local oscillators using molecular absorption lines

We describe the frequency-lock (FL) system for local oscillators in receivers in the 130 to 360 GHz range, using the resonance lines of molecules with a known absorption spectrum. The functions of a frequency discriminator, a diplexer, and a noise rejector are performed by a Mach-Zehnder interferometer with a gas cell. Deceased Institute of Applied Physics of the Russian Academy of Sciences, Nizhny Novgorod, Russia. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 41, No. 11, pp. 1399–1404, November, 1998.     

Temperature dependence of pressure broadening of the N = 1− fine structure oxygen line at 118.75 GHz

The absorption profile of the N = 1− fine structure line of oxygen was recorded by a resonator spectrometer at a frequency range of 110-130 GHz at atmospheric pressure and different temperatures ranging from −21 °C up to +22 °C. Analysis of the observed line shape allowed determination of the temperature dependence of the line pressure broadening. The measured value of the temperature exponent is n = 0.74(5) for self-broadening. Consistency of the measurements is supported by simultaneous measurements of the line intensity, the line mixing parameter and the line center frequency, and by comparison of obtained values with previously known data.