Quantum interference effects of γ radiation under crossing-anticrossing of nuclear levels in an RF field

The quantum interference effects occurring in resonant scattering of a γ photon in the multilevel γ-optical medium ⁵⁷Fe, affected by an external RF field, have been theoretically investigated. It is shown that a significant reconstruction of the hyperfine structure of nuclear states leads to the interference of partial forwardscattering amplitudes of a γ photon and, therefore, to a significant change in the nuclear refractive index of the γ-optical medium, depending on the amplitude, frequency, and phase of the external RF field. The conditions are found under which the effect of electromagnetically induced transparency can be observed in the technique of in-phase detection of γ photons.     

Mössbauer studies of sublattice magnetization curves of ferromagnets with several species of characterizing ions

The paper gives a model of a local molecular field describing the magnetization curves in iron garnets separately according to magnetic sublattices. It takes account of the relation between the ion distribution over the lattice sites as well as the values of the local magnetic field and the parameters of the superexchange interaction in such materials. The relations obtained are compared with the data of Mössbauer and NMR spectroscopy.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 6, pp. 83–88, June, 1979.     

Conversion of n-butylamine in the course of synthesis from carbon monoxide and hydrogen

Summary The possibility of the direct synthesis of secondary and tertiary aliphatic amines from carbon monoxide, hydrogen and a primary alkylamine on fused iron catalysts was demonstrated.     

On linear groups containing the commutator subgroup of an orthogonal group of index greater than 1

Minsk. Translated fromSibirskiî Matematicheskiî Zhurnal, Vol. 33, No. 5, pp. 15–21, September–October, 1992.     

On the surface viscosity at the boundary between phases

The equations of motion of the interphase boundary are considered. It is shown that the conditions at the surface separating the phases obtained in /1, 2/ by different methods, are identical. The study of the dynamics of the fluid-fluid interface was initiated by Bussinesq /3/ who postulated a linear relationship between the surface stress tensor T_β and the strain rate tensor S_β, assigning two viscosity coefficients to the surface, the dilatation coefficient k (the analog of volume viscosity) and the two-dimensional shear viscosity . In the three-dimensional coordinate system two of whose axes u¹ and usu2 coincide with the axes of any coordinate system at the surface and whose third axis u³ is perpendicular to the surface, his results have the form Tβ = [γ + (k - )θ]a_β + S_β , θ = a^βS_β, V_{, β} = r_{. β} — v_sb_β,      

Theory of quasienergetic phenomena in nuclear gamma resonance

An analysis is conducted of the resonance scattering of quanta when a ferromagnet scatterer experiences a single exposure to a strong radiofrequency field which is at resonance with respect to the Zeeman system of nuclear sublevels. The role of the quasienergetic spectrum arising in these conditions (analogous to the effect of a strong field in optics) in the formation of a scattering spectrum and, in particular, the intensity of the additional lines is demonstrated. The relation of the results obtained to those of other workers is discussed.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 9, pp. 111–114, September, 1981.     

A Free‐Radical Prompted Barrierless Gas‐Phase Synthesis of Pentacene

A representative, low‐temperature gas‐phase reaction mechanism synthesizing polyacenes via ring annulation exemplified by the formation of pentacene (C₂₂H₁₄) along with its benzo[a]tetracene isomer (C₂₂H₁₄) is unraveled by probing the elementary reaction of the 2‐tetracenyl radical (C₁₈H₁₁^.) with vinylacetylene (C₄H₄). The pathway to pentacene—a prototype polyacene and a fundamental molecular building block in graphenes, fullerenes, and carbon nanotubes—is facilitated by a barrierless, vinylacetylene mediated gas‐phase process thus disputing conventional hypotheses that synthesis of polycyclic aromatic hydrocarbons (PAHs) solely proceeds at elevated temperatures. This low‐temperature pathway can launch isomer‐selective routes to aromatic structures through submerged reaction barriers, resonantly stabilized free‐radical intermediates, and methodical ring annulation in deep space eventually changing our perception about the chemistry of carbon in our universe.