The peculiarities of radiation of chiral photonic crystals with isotropic defect layer

The peculiarities of defect modes and reflection spectra of chiral photonic crystals (CPC) with an isotropic defect for various thicknesses of the defect layer were investigated. The peculiarities of the spectra of photonic density of the state (DOS) and those of the intensity at the center of the defect were investigated, too. It was shown that there is one more possibility of tuning of laser emission - by the change of the defect layer thickness - in CPCs doped with laser dyes (with resonance atoms) and with an isotropic defect. It was shown that the given system can work as a tunable narrow-band filter (or mirror) with tunable wavelength width and tunable location of frequency of the complete transmittance (reflection) band. The radiation peculiarities of these systems were discussed. It was shown that in certain conditions an anomalous strong radiation can be observed for defect modes, and low-threshold laser generation is possible, again, for these modes. It was also shown that radiation suppression is possible for defect modes. The peculiarities of group velocity, group velocity dispersion and non-reciprocity were studied.     

Detection of casimir photons with electrons

We propose a method for the detection of a dynamical Casimir effect. Assuming that the Casimir photons are being generated in an electromagnetic cavity with a vibrating wall (dynamical Casimir effect), we consider electrons passing through the cavity to be interacting with the intracavity field. We show that the dynamical Casimir effect can be observed via the measurement of the change in the average or in the variance of the electron’s kinetic energy. We point out that the enhancement of the effect due to finite temperatures makes it easier to detect the Casimir photons.     

Electrical properties of thermal donors formed in silicon under elastic tensile stress

The electrical properties of thermal donors formed in the bulk and near-surface regions in silicon samples with (3–9) × 10¹⁷ cm⁻³ oxygen concentrations under elastic tensile stress σ of about 1 GPa have been studied. The original method allowing us to control an introduced elastic tensile stress during the thermal donor’s formation at T = 450°C by a double-crystal X-ray diffractometer has been used. The formation of thermal donors in silicon with a high oxygen concentration of 9.3 × 10¹⁷ cm⁻³ under tensile stress has been found to be less effective than in silicon with a low oxygen concentration of (3–5) × 10¹⁷ cm⁻³. Single-charged donors are formed in silicon with a low oxygen concentration under tensile stress while double-charged donors are formed in silicon with a high oxygen concentration.     

A study of the reaction of pentacyclic triterpenoids with concentrated sulfuric acid

Summary The conditions for the reaction of triterpenoids with concentrated sulfuric acid have been studied by the method of mathematical planning, and the optimum conditions for performing this reaction have been found.Pyatigorsk Pharmaceutical Institute. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 294–296, May–June, 1971.