The results of investigation of the luminescence under photo- and electroexcitation for four new compounds are presented. The spectral properties and photoluminescence are studied in ethanol, chloroform solutions and in films formed by thermovacuum deposition (TVD). The phosphorescence of compounds is investigated in ethanol at 77K temperature. The phosphorescence times of molecules are given. The electroluminescence is obtained in multilayered structure ITO/PEDOT/NPD/L /Ca/Al. It is shown, that spectral region of the photoluminescence of TVD films and electroluminescence coincide. Relations of electroluminescence efficiency with molecule structure, photoluminescence quantum yield and possibility of thermally activated delayed fluorescence are discussed.
Ways of improving autocollimation sensors for monitoring angular displacements are analyzed. The results of an
analysis of control elements based on tetrahedral reflectors with flat and cone reflecting sides are presented. The
technical characteristics of experimental models of control elements are presented. The features of tetrahedral reflector as
the control elements for three-axis angular sensors are discussed.
Photophysical and lasing properties of the well known PM567, PM580 and PM697 and three new
dipyrromethene derivatives are presented. The laser efficiency and spectrum characteristics were investigated as
functions of dye concentration and pumping intensity in ethanol solutions under second harmonic of Nd-YAG-laser.
Laser characteristics and photostability for PM567 are presented also in the solid state matrixes
The spectral-luminescent and lasing properties of the 3-substituted-7-hydroxycuomarins derivatives are studied experimentally and using quantum-chemical calculations using INDO method with spectroscopic parameterithation. The photophysical processes in these compounds were analyzed.
A method of fluorescent spectroscopy is used to study phototransformations of <i>4</i>-methyiphenol and its NH<sub>2</sub>-substitutes in water excited by UV radiation of different sources. It is demonstrated that the photophysical and photochemical properties of these molecules depend on the electronic state to which they are excited.
The important problem of modern laser medicine is the decrease of an exposure of biological tissues outside of an operational field and can be solved by optical radiation limiting. Organic dyes with reversibly darkening can be placed onto surfaces of irradiated tissues or can be introduced in solder for laser welding of vessels.
The limiting properties of a set of nontoxic organic compounds were investigated. Nonlinear optical properties of dyes having reverse saturable absorption (pyran styryl derivatives, cyanine and porphyrine compounds) were studied under XeCl and YAG:Nd (II harmonics) lasers excitation. The effect of attenuation of a visible laser radiation is obtained for ethanol solutions of cyanines: radiation attenuation coefficient ( AC) = 25-35 at N/S = 100-250 MW/cm<sup>2</sup>. In water solutions of such compounds in UV spectrum range AC ≈ 10. The spectral characteristics of compounds appeared expedient enough to operational use in laser limiters (broad passband in visible range of a spectrum). Under the data of Z-scanning (the scheme F/10) value AC ≈ 70 was reached. The limiting of power laser radiation in visible (λ = 532 nm) and UV- (λ = 308 nm) spectral region and nanosecond pulse duration (7 -13 ns) across porphyrine solutions and their complexes with some metals (13 compounds) was investigated too. The comparative study of optical limiting dependence on intensity of laser radiation, solvent type and concentration of solutions was carried out for selecte wavelength. There was shown a possible use of pyran styryl derivatives DCM as limiters of visual laser radiation.
To understand a mechanism of laser radiation limitation the light induced processes were experimentally and theoretically studied in organic molecules. The quantum-chemical investigation of one cyanine compound was carried out.
There were noted the perspectives of laser radiation limiting by application of inverted schemes of traditional laser shutters. Usage of phenomena of light -induced opalescence in one-component liquids and spinodal decay in stratifying liquid solutions is proposed.
The methyl-substituted phenols(o- and p-cresol) photolysis under UV-excitation from KrCl-laser in water solutions are presented. The irradiated solutions were investigated by spectroscopic methods. The comparison of the KrCl-laser irradiation effects with and without argon bubbling for phenol, o- and p-cresol was realized for the first time.
To study of halogen a substituted phenols photochemical property in the neutral media under action of the man-made sources of excitation the purpose of the present work. There are exciplex KrCl laser and high-frequency excilamp of a grow discharge on same molecules. The efficiency of a photolysis by the spectroscopic methods estimated. Comparison of lamp and laser photolysis of substituted phenols occurs.
A study of the phenol, 4-chlorophenol and 4-bromophenol aqueous solutions, photolysis under UV-irradiation from capacitive discharge KrCl- and XeBr-excilamps at different wavelengths have been undertaken. To specify photolysis efficiency the irradiated solutions have been investigated by spectroscopic methods. To account for obtained results, the quantum-mechanical computation has been invoked.
Phenol and 4-chlorophenol water solutions photolysis under UV-excitation from KrCl-laser and capacitive discharge KrCl- excilamp are presented. The irradiated solutions have been investigated by spectroscopic methods. The comparison of the KrCl-excilamp and KrCl-laser irradiation effects has been realized for the first time.
Lasing properties and photostability of 4,4'-CO<SUB>2</SUB>C<SUB>4</SUB>H<SUB>9</SUB> bis-substituted paraterphenyl and azacoumarin AClF emitting in the blue-green region of the spectrum in poly(methyl methacrylate) and ethanol pumped by a XeCl excimer laser and both pyrromethene 580 and phenalemine 512 pumped by a Cu laser emitting in the red region of the spectrum have been investigated.
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 NO<SUB>2</SUB> and SO<SUB>2</SUB> 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 NO<SUB>2</SUB> content in the atmosphere.
Amplification of stimulated Raman scattering (SRS) radiation of ethanol in a polydispersion of microdroplets of ethanol solution of Rhodamine C is obtained experimentally when irradiating the droplets with laser pulses of 0.532 micrometer wavelength.
Lasing properties of two dyes in polymeric matrix radiating in blue-green region of the spectrum pumped by a XeCl laser are studied. The lasing efficiency and photostability of the solid state active media are compared with corresponding characteristics of the same liquid active media.
Amplification of stimulated Raman scattering radiation of ethanol in a polydispersion of microdroplets of ethanol solution of Rhodamine C is obtained experimentally when irradiating the droplets with laser pulses of 0.532 micrometers wavelength.
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 10<SUP>23</SUP> to 10<SUP>26</SUP> phot/cm<SUP>2</SUP>s. Dynamics of losses in laser pulses in coumarine substituted was studied under XeCl laser pumping.
The intramolecular energy transfer (IET) in bifluorophoric molecules was researched experimentally and theoretically with the quantum-chemical method. It is shown, that IET realizes through the internal conversion process in bifluorophoric molecules depends on a mutual orientation of a donor and an acceptor and a length of (CH<SUB>2</SUB>)<SUB>n</SUB>- bridge. The coefficient of IET and the lasing efficiency of the bifluorophores were estimated experimentally.
Theoretical and experimental studies of trans-stilbene (TS) and TS-based bifluorophores are presented. The emission properties have been investigated under excimer XeCl<SUP>*</SUP>-laser excitation ((lambda) equals 308 nm). It is shown that under favorable conditions, i.e. with short excitation pulses (approximately 3-4 ns), stimulated emission dominates over trans-cis photoisomerization process. The TS emission efficiency is low (approximately 4%). In this study we present the calculated absorption spectra for TS, its fluorosubstituted derivative, 2,6- difluorostilbene. Analysis of the electronic excited states shows that the internal conversion processes are the basic channel of the excitation energy degradation (k<SUB>ic</SUB> equals 10<SUP>12</SUP>s<SUP>-1</SUP>) for the TS molecule. The results obtained show that lasing efficiency of TS-CH<SUB>2</SUB>-C120 is lower than that of C120. The mixed character of the third electron state in the bifluorophore (this is the lowest excited state of the donor fragment) results in enhanced singlet-triplet conversion between S<SUB>3*</SUB> and T<SUB>11*</SUB> states. This channel of the excitation energy degradation is responsible for reduced lasing efficiency of the test bifluorophore.
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.