Evgenii N. Tel'minov

Theoretical and experimental investigation of photophysical properties of Zn(DFP SAMQ)2.

Theoretical calculations and experimental measurements were carried out for the investigation of spectroscopic and photophysical properties of Zn(DFP SAMQ)2 complex. The rate constant of intersystem crossing and the radiative rate constant were calculated using ab initio method. The rate constant of the internal conversion was estimated using the received calculated values and the experimental fluorescence quantum yield. It was shown that the main mechanism for the deactivation of the excited electronic energy of the first singlet excited state is the process of internal conversion.

Emission of Concentrated Solutions of Organic Compounds Excited with High-Power Laser Radiation

Specific features of emission of concentrated (C ≤ 1.2·1019 cm–3) solutions of organic molecules (rhodamine 6G, rhodamine C, phenalemine 512, and substituted paraterphenyl (LOC-1)) are investigated as functions of the exciting photon energy (at λexc = 308 and 532 nm) and power density of exciting radiation (up to 1 GW/cm2). One of the observed emission types – band emission – is studied. The intensity of band emission (its short- and long-wavelength maxima) is investigated versus the exciting radiation power density, and its time and polarization characteristics are also analyzed. The results obtained together with the specific features of the emission spectrum of concentrated rhodamine-C solution, measured after passage of sounding radiation with maximum at the wavelength equal to that of the short-wavelength maximum of band emission, demonstrate that the band emission is simply superfluorescence.

Phototransformations of Organic Compounds upon Powerful Laser Excitation under Nonlinear Absorption Conditions

Phototransformations, stationary- and induced-absorption spectra, and emission spectra of solutions of a dicarboxyalkyl derivative of p-terphenyl, as well as the transmission of exciting radiation from a XeCl laser by these solutions, were studied depending on the radiation intensity and degree of polarization. The reasons for variation in the quantum yield of phototransformations depending on the parameters of exciting radiation are discussed.

Laser system: powerful XeCl* laser-dye laser for ecological monitoring of the atmosphere

The present paper reports the experimental results and design of the laser systems developed for lidar experiments. The laser systems with radiation energy of hundreds of millijouls at each of several wavelengths allow to detect NO2 and SO2 atmospheric impurities. At the moment the laser system: powerful XeCl*-laser-dye laser is incorporated in a lidar developed at the Scientific Research Institute of Space Equipment (Moscow) for measurements of NO2 content in the atmosphere.

Specific features of spontaneous and stimulated molecular radiation in high-power laser beams

Fluorescence characteristics of 2-(4-pyridyl)-5phenyloxazole (4PyPO) and trans-stilbene has been studied under high power XeCl laser excitation. Anomal fluorescence phenomenon has been found. Gain and losses were measured in 4PyPO active media in range of excitation rate from 1023 to 1026 phot/cm2s. Dynamics of losses in laser pulses in coumarine substituted was studied under XeCl laser pumping.

Effect of excitation conditions on photostability of 2-(4pyridyl)-5 phenyl)oxazole laser media

A method of photostability examination of dye active media is described. Quantum yield of phototransformation, relative yield of some final photoproducts, as well as laser lifetime of 2- (4pyridyl)-5 phenyl)oxazole (4PyPO) ethanol solutions were measured. These characteristics were studied as functions of dye concentration, excitation power, and pulse duration, as well as type of irradiation (by means of spontaneous or lasing). Transient T-T absorption spectra were monitored. Effects of different additions into solution of T-T absorption and photostability of the medium were investigated. Improvement in lifetime of 4PyPO active media is discussed.