Manifestation of gyrotropy upon light scattering in paratellurite

Upon scattering of laser radiation at different wavelengths, three optical effects—rotation of the plane of polarization of linearly polarized light, dependence of the specific rotation on the radiation wavelength, and the dependence of the scattered light intensity on the angle between the scattered and incident beams—are simultaneously observed. The intensity distributions of the scattered laser light at 0.488, 0.531 nm, and 0.633 μm along the optical axis of a thick sample of a TeO₂ single crystal are visualized. Based on the patterns obtained, the values of the specific rotation are calculated, and the curve of the optical rotation for the visible range is obtained.     

Optical Materials for the THz Range

Optics and Spectroscopy - The properties of optical materials usable in the terahertz (THz) spectral range, which is the boundary between the optical and radio ranges, are examined. The relevance...     

Edge vibration of a pre-stressed semi-infinite strip with traction-free edge and mixed face boundary conditions

Edge-vibration, and associated resonance phenomena, is investigated in respect of a semi-infinite strip composed of pre-stressed incompressible elastic material. The strip is assumed to have a traction free outer edge, with the upper and lower edges subject to some simple mixed boundary conditions. The frequency of the modes of free edge-vibration are shown to depend on the surface wave speed. Moreover, when the normal pre-stress approaches one of two critical values, associated with the vanishing of the surface wave speed, the edge spectrum density of the boundary value problem increases significantly. This problem then provides an example for which the famous Weyls hypothesis, stating the edge spectrum is secondary in comparison with the whole bodys spectrum, is not true. However, the corresponding theorems statement is valid only with imposition of the Shapiro-Lopatinsky condition, which is not satisfied in this case. Variation of the pre-stress is also shown to greatly influence the resonance frequency arising in the forced vibration problem, to the extent that the phenomenon of resonance may be totally removed.     

Radiothermoluminescence. I. Radiothermoluminescence for investigation of thermal and radiation-induced crosslinking of rubber mixtures

Phase heterogeneity of vulcanizates based on cis-polybutadiene (cis-Europrene) and SBR (Europrene 1500) blends obtained by radiation, thermal, two-stage radiation-thermal, and two-stage thermal-radiation processes was investigated by the radiothermoluminescence method. Unvulcanized blends of these polymers are found to be heterogeneous, exhibiting two glass transition temperatures T_g, which coincide with the values for the initial components. Following vulcanization, the difference between the two T_g values for a polyblend decreases. The decrease is more distinct for polyblends crosslinked at high temperatures. When the vulcanization temperature exceeds 140°C and the crosslink density (or 1/M_c) exceeds 5 × 10^?5–1 × 10^?4 mole/cm³, the glass temperature ranges of the crosslinked blend are practically superimposed. Such crosslinked mixtures should be considered pseudohomogeneous in phase.     

Free localized vibrations of a semi-infinite cylindrical shell

Free vibrations of a semi-infinite cylindrical shell, localized near the edge of the shell are investigated. The dynamic equations in the Kirchhoff-Love theory of shells are subjected to asymptotic analysis. Three types of localized vibrations, associated with bending, extensional, and super-low-frequency semi-membrane motions, are determined. A link between localized vibrations and Rayleigh-type bending and extensional waves, propagating along the edge, is established. Different boundary conditions on the edge are considered. It is shown that for bending and super-low-frequency vibrations the natural frequencies are real while for extensional vibrations they have asymptotically small imaginary parts. The latter corresponds to the radiation to infinity caused by coupling between extensional and bending modes.