Deduction of relaxation parameters from saturation in non-uniformly broadened ESR lines

A mode with noninteracting spin packets is used to calculate the saturation curves of lines with Gaussian and Lorenzian shapes, provided that the steady magnetic field is modulated at a low frequency. Curves are given that allow deduction of the width of the spin packets from the observed saturation curves. Tests are reported for the radicals produced by -rays in d, l-alanine, glycine, and phenol; the relaxation times T₂ are found to be respectively 2·10^–8, 3.8·10^–8, and 2.7·10^–8 sec. In the first two cases T₂ agrees roughly with the width of the spin packets calculated from the radical concentrations.     

New Type of Neutral Binuclear Spin-Crossover Complex of Iron(III) with Twist of Two Disulfide Bridges as a Product of Electrochemical Oxidation of [FeIII(5Cl-thsa)2]− Anions

As a result of the electrochemical oxidation process, the [Fe^III(5Cl-thsa)₂]⁻ spin-crossover (SCO) anion with N₂S₂O₂ coordination sphere transforms into N₄O₂-coordinated Fe^III SCO neutral binuclear complex 2 with twist of two disulfide bridges. Each dimeric complex is a binuclear double-stranded helicate with similar chirality of both Fe centers. The crystal structure of the complex 2 ⋅ 3H₂O at 100 K has a monoclinic C2/c space group and contains large cavities (about 21.5 % of the unit cell volume) half-filled by 3 water molecules per one dimer. The N₄O₂ coordination of iron(III) with two oxygen atoms (−O⁻) of phenoxy groups, two imine-type (−N_im=) nitrogen atoms of azomethine groups, one amidrazone-type (=N_amidH) nitrogen atom and one ionized terminal group (−N_ionizH) of nitrogen has not been observed in CCDC so far. The oxidation state of the iron atoms in the dimeric complex was confirmed by ⁵⁷Fe Mössbauer spectroscopy on 90 % enriched ⁵⁷Fe sample. Mössbauer spectra and dc magnetic measurements demonstrated the partial HS-HS→LS-LS SCO in the 185–225 K temperature range. The details of the structure of complex 2 and the features of its magnetic properties were refined by theoretical analysis based on DFT calculations. The B3LYP* functional correctly predicting the energy of the spin-crossover process was revealed.     

Investigation of laser energy conversion into plasma x-rays in the system Iskra-4

We present results of experimental and computational investigation of laser plasma emission in the soft x-ray spectrum. Plasma has been produced by irradiating a gold target with subnanosecond pulses at the first and second harmonics of an iodine laser. It has been shown that approximately half of the absorbed laser energy is converted into soft plasma x-rays.Presented at bilateral international seminar of High Temperature Laser Plasma and High Gain Iodine Lasers held on 4 July 1991 in the Inst. of Physics, Czechosl. Acad. Sci., in Prague (organized by Division of Optics of the Inst. of Physics, Czechosl. Acad. Sci., and Physical Section — Plasma Division of the Union of Czech Mathematicians and Physicists).     

Tris(2,6-dimethoxyphenyl)antimony Diazide: Synthesis and Structure

Tris(2,6-dimethoxyphenyl)antimony diazide has been synthesized and characterized by X-ray diffraction. The antimony atoms in four crystallographically independent molecules have a distorted trigonal pyramidal coordination. Axial angles range within 174.57°–178.95°.     

Synthesis and structure of tetraphenylantimony cyanamide

The reactions of tetraphenylantimony chloride and bromide with carbamide were used to obtain tetraphenylantimony cyanamide in yields of 52 and 48%, respectively. According to X-ray diffraction data, the antimony atom has a distorted trigonal bipyramidal coordination with axial cyanamide and aryl groups [axial CSbN angle 177.76(7)°, Sb-C 2.107(2)-2.167.2, Sb-N 2.3383(18) Å].     

Preparation and structure of tri-p-tolylbismuth dibromide

Interaction of tri-p-tolylbismuth with bromine in carbon tetrachloride has yielded tri-p-tolylbismuth dibromide. According to X-ray diffraction studies, bismuth atoms in both symmetrically independent dibromide molecules were in distorted trigonal bipyramid surrounding with equatorial aryl substituents.     

Synthesis of new 1-(3,4-dimethylphenyl)-1,5-dihydropyrazolo[3,4-<Emphasis Type="Italic">d</Emphasis>]pyrimidin-4-one derivatives

New substituted pyrazolo[3,4-d]pyrimidin-4-ones have been synthesized as a result of a series of transformations including hydrolysis of ethyl 5-amino-1H-pyrazole-4-carboxylates, cyclization of the carboxylic acids thus obtained to pyrazolo[3,4-d][1,3]oxazin-4(1H)-ones, and treatment of the latter with substituted anilines. The final pyrazolo[3,4-d]pyrimidin-4-one derivatives can also be synthesized from 5-(arylamido)-1H-pyrazole-4-carboxylic acids in the presence of a catalytic amount of anhydrous zinc(II) chloride.     

Quantization of a Hamiltonian system with an infinite number of degrees of freedom

We propose a method of quantization of a discrete Hamiltonian system with an infinite number of degrees of freedom. Our approach is analogous to the usual finite-dimensional quantum mechanics. We construct an infinite-dimensional Schrödinger equation. We show that it is possible to pass from the finite-dimensional quantum mechanics to our construction in the limit when the number of particles tends to infinity. Rigorous mathematical methods are used.