Photoluminescence of epoxy resin modified by carbazole and its halogen derivative at 82 K

The spectra and relative quantum yield of fluorescence and phosphorescence were measured for 9-(2,3-epoxypropyl)carbazole (EPK) added to epoxy resin (R) (R₅EPK – 5% weight content of the carbazole group in a polymer) and its mono and dihalogen derivative (Cl and Br). The materials under study have excellent mechanical properties. At 82 K photoluminescence (PL) spectra of these materials are composed of fluorescence (FL) and phosphorescence (PH) components while at 280 K, PH component is not observed. The vibrational frequencies of fluorescence and phosphorescence for R₅EPK were determined using Gaussian deconvolution. A decrease in the fluorescence and an increase in the phosphorescence quantum efficiency were observed after chemical bonding of heavy atoms Cl and Br.     

Mode tuning and hysteresis behaviour of Gunn-effect cavity-controlled generator

It is shown that, for both the bias voltage and the resonant circuit oscillation period, a range exists in which two values of oscillation amplitude are possible. These values correspond to the mixed mode and to the under-voltage resonant mode. The conditions for the transition from one mode to another are investigated.     

A calibration kit of fluorescent standards for the UV spectral range of 230–410 nm

A calibration kit of universal fluorescent standards for the spectral range of 230–410 nm, developed on the base of inorganic solutions of Ce(III) and Pr(III) salts with anions having no intensive absorption bands in the standard operational area was investigated. The kit is intended to calibrate the spectral responsibility of spectrometers, spectroradiometers and spectrofluorimeters in the UV spectral range, and to carry out luminescence quantum yield and decay kinetics measurements.     

Interactive display technologies

Abstract— The current state of the art of interactive displays, the main principles of their operation, and their functional characteristics are reviewed. Special attention is given to interactive displays with contactless control; in particular, to photo‐sensitive displays. A number of photo‐sensitive display cell designs are considered, as well as the problems related to the production of such cells. The results of the authors' research in this field are presented.     

Gunn-effect cavity-controlled generator

Equations describing oscillations of a Gunn generator coupled to an external resonant circuit in some cases coincide with the equations of motion of a 1-dimensional harmonic oscillator changing its equilibrium point and friction coefficient by jumping. The condition for the phase trajectory to be closed results in a simple dependence between the resonant-mode parameters and gives also tuning limits for such a mode.