Rimma T. Kuznetsova

Spectral and luminescent properties of some porphyrin compounds in different electronic states

The spectral and luminescent properties of some derivatives of tetraphenylporphyrin are studied at different concentrations of these compounds; the spectra of neutral and ionic forms are interpreted; and the quantum yields of ordinary and, in some cases, short-wavelength fluorescence from highly excited states are determined. The spectra of transient absorption from excited states, existing in the time range of tens of nanoseconds, are measured, and the quantum yields of formation of triplet molecules are estimated. Hypotheses regarding the mechanism of phototransformations of some porphyrins in chloroform are put forth.

Phototransformations of Phenols in Aqueous Solutions under Different Excitation Modes

The photolysis of aqueous solutions of two widespread environmental organic ecotoxicants—phenol and 4-chlorophenol—on excitation by UV radiation from a KrCl exciplex laser and a glow-discharge KrCl excilplex lamp was studied. The irradiated solutions were studied by spectroscopic techniques. The laser and lamp photolyses were compared.

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.

Spectral-luminescent, photochemical, and nonlinear optical properties of some cyclotetrapyrrole derivatives in liquid and solid media

Spectral-luminescent, nonlinear, and photochemical characteristics of some cyclotetrapyrrole compounds are investigated. Methods of investigation are described, and results obtained that can be used for the development of laser limiters and phosphors are presented. It is demonstrated that the protonation efficiency changes under excitation and when going from liquid solutions to solid media. A new assumption on the influence of solution acidification on the limitation of high-power emission and photostability is discussed.

A Spectroscopic Study on Ground- and Excited-State Proton Transfer Reactions of Coumarin Derivatives

Interaction of Coumarin 1, its 3-aldehyde derivative, and biscoumarin with solvents of varying acidity (water and ethanol with an alkali or acid admixture) was studied by following changes in their absorption and luminescence properties. The reasons for weak emission ability of neutral ethanolic solutions of 3-substituted derivatives of Coumarin 1 were revealed.

Blue-green laser radiation from dyes in matrix

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.

Photonics of boron fluoride and zinc dipyrromethene complexes

Spectral, photophysical, photochemical characteristics for mononuclear and binuclear dipyrromethenes in complexes with BF2 (BODIPY), bis-BODIPY and bis-helicates ([Zn2(L)2]) are described. The role of substituents (type and location in the ligand) and the medium in which dipyrromethene complexes are placed (solvents, solid-state matrices), the effect of different complexing agents (p- and d-elements) on the photonics of the complexes are discussed. The results of studying the lasing and photochemical properties of complexes under the action of laser irradiation are presented. In addition, for the described complexes the stability in the ground and excited states in protic media are estimated. Based on the analysis of the results discussed possibilities of practical application of these compounds to creating various optical devices.

Solid-state active media on the base of silica matrices doped with UV and visible laser dyes

New results on the influence of the composition of a silica gel-matrix and the process of its production on the spectral, lasing and photochemical properties of embedded luminophores: rhodamine, phenalemine, oxazole, coumarine and other dyes series, which have lasing in the UV, blue-green and red spectral regions under excitation by poweful laser radiation of various wavelength (308 and 532 nm) and intensity (from 0,1 to 100 MW/cm2) have been obtained. The shortest-wavelength lasing is achieved for silica solid matrices with para-terphenyl (342 nm). Optimal conditions have been selected and the lasing of thin silica solid films doped with aminocoumarine (457 nm) with resource exceeding that in solutions has been obtained. It is established, that organic luminophores are fixed in nanodimensional pores of silica and hybrid matrices by specific interactions, that compete with the association of dyes.

Spectroscopic investigation of new bis(phthalocyaninato)lanthanide complexes for optical limitation of powerful laser radiation

We synthesized and studied sandwich complexes where a lanthanide is coordinated with two phthalocyanine rings. Study of nonlinear optical properties was tested with using the XeCl (308 nm, 10 ns) and second harmonic of Nd:YAG (532 nm, 15 ns) laser. In this experiment were estimated the coefficient of limitation, quantum phototransformation yields and the quantum yield in the triplet state from spectral-luminescent characteristics. Much attention is given to studying of ionic and neutral forms of sandwich complexes in the basic and excited states.

The new optical materials for turning laser active media and light emitting devices

The spectral-luminescent, photochemical and lasing characteristics of some laser dyes: rhodamine, phenalemine, oxazole and p-terphenyle derivatives, incorporated into solid silica matrices during sol-gel process with different composition of silica alkoxides and geometrical forms of solid samples were studied. It is shown that optical properties of thin silica gel-films (<1 /spl mu/m) are doped with organic molecules have some peculiarities compared with bulk gel-matrices. The lasing of bulk matrices with dyes and traveling wave lase in some thin films under laser excitation was observed. The proton transfer from solid matrices to the proton acceptor centre of some dyes is observed at the ground and the excited states. The molecular and laser photostability of dyes in solid silica matrices was determined, is shown that it is higher compared with the photostability of ethanol solutions of the same dyes.