Two-dimensional NQR spectroscopy of forbidden transitions

Two-dimensional NQR spectroscopy has been realized experimentally for a direct method of detecting and recording forbidden transitions. The cross peaks of the two-dimensional spectra were used to assign the lines in the complex spectra.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 8, pp. 73–75, August, 1991.     

Anisotropy of the mechanical properties of cross-linked poly(n-butyl methacrylate)

Mechanical properties of cross-linked poly(n-butyl methacrylate) synthesized under shear stress are reviewed. The effect of shear stress rate and of the cross-linking agent concentration on the resulting polymer properties was demonstrated.Kiev Branch, All-Union Scientific-Research Institute of Complex Polygraphy Problems in Special Types of Printing. Institute of the Chemistry of High-Molecular-Weight Compounds, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Mekhanika Polimerov, No. 1, pp. 150–152, January–February, 1972.     

The influence of resonance IR laser radiation on magnetoabsorption in quantum wires

The coefficient of interband absorption of a weak electromagnetic wave by quantum wires in a transverse magnetic field and an intense laser radiation field is calculated. It is shown that, if the laser radiation frequency is equal either to the size quantization frequency (dimensional infrared resonance) or to a hybrid frequency (magnetoinfrared resonance), laser illumination can determine the shape of absorption oscillations. In particular, it is shown that the second magnetoabsorption peak is split into two peaks, the half-widths of which and the distance between which depend on the intensity of resonance laser radiation. The influence of the polarization of IR radiation on the interband absorption in quantum wires is discussed. The dynamics of the frequency dependence of the optical absorption coefficient with increasing intensity of resonance laser radiation is studied.     

Multiphonon absorption of light in quantum-well systems in uniform electric and magnetic fields

The effect of a transverse electric field on the multiphonon absorption of light in quantum-well systems in a uniform magnetic field aligned parallel to the spatial quantization axis is investigated. It is shown that, when the interaction of an electron with long-wavelength vibrations is taken into account, the half-width of the absorption line does not depend on the electric-field vector E. As the electric field strength increases, the maximum of the light absorption shifts toward the long-wavelength range and decreases. The effect of the electric field on the shape of the zero-phonon line and first vibrational satellites is analyzed with due regard for the interaction of charge carriers with optical phonons. It is demonstrated in particular that the half-width of the zero-phonon line substantially depends on the electric-field vector E and can reach several millielectron-volts at the electric field strength E = 2 × 10⁴ V/cm.     

Electrically induced luminescence in parabolic quantum wells in a magnetic field

Interband luminescence in a parabolic quantum well is studied in applied electric and magnetic fields. It is shown that the luminescence peak is displaced towards higher frequencies with increasing magnetic field strength, while an increase in the electric field strength causes a displacement of the emission peak towards the long-wave region and a decrease in its amplitude. The theoretical results are compared with the experimental data. The existence of a new electromagnetic-wave emission channel (electrically induced luminescence) associated with indirect optical transitions is predicted. The frequency dependence of the electrically induced radiation is computed, taking into account the interaction of an electron with acoustic and optical phonons. It is found that the half-width of the luminescence peak increases with the electric field strength.     

NQR line intensities of14N in a method with field cycling

Certain processes of exciting the evolution of a spin system by video-frequency pulses of magnetic field in a method with field cycling are theoretically analyzed for¹⁴N NQR. Possibilities of a direct and an indirect method of detection for NMR-NQR spectroscopy in zero field are considered.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 4, pp. 61–65, April, 1989.