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.
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
(P(MMA=13%POSS), PMMA).
Spectral-luminesnce, nonlinear-optical and photochemical characteristics of metal complexes with new
tetraphenylporphyrin (TPP) derivatives, with atom Lu(III) or Gd(III) in the ligand-complexone or as a central ion, in
liquid and frozen solutions and in state-solid polymer matrices also are studied. The limiting coefficient (LC=T0/TW) at
power density about 250 MW/cm2 chosen as gauge of nonlinear-optical properties. Phototransformation quantum yield
under 2nd harmonic of Nd-YAG-laser irradiation (φ532) chosen as gauge of photostability. Results of investigation show
significant nonlinearity of studied substances caused by reverse saturable absorption. Compounds photostability quite
enough, spectral characteristics of irradiated samples are evidence of protonated nature of photoproduct, which in one's
part make contribution to power radiation absorption.
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.
The time course of protoporphyrin and coproporphyrin concentrations in patients' erythrocytes during physiological pregnancy and in cases of toxemia was studied with spectral-luminescence method. Substantial care and attention are given to processing of luminescence spectra of mixtures of endogeneous porphyrines, prepared from erythrocytes of patients. This processing is very important and necessary for practical application of this method in medicine and biology. Our results show, that the luminescence method allows making earlier diagnostics of toxemia and estimating the degree of gravity of the disease.
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.
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.
KEYWORDS: Solid state lasers, Solid state physics, Dye lasers, Absorption, Bioalcohols, Liquids, Gas lasers, Polymethylmethacrylate, Solid state electronics, Ultraviolet radiation
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.
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 (CH2)n- bridge. The coefficient of IET and the lasing efficiency of the bifluorophores were estimated experimentally.
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.
Since the late 1960s atherosclerotic plaque (AP) laser ablation techniques have been developed. Clinical data obtained with CW laser vaporization AP shows significant impairment of tissues close to plaque with following severe complications in postoperation period. The use of excimer pulsed laser decreases the harmful effects of laser radiation. However, data on spectrum of energy absorption by molecular AP structures are required for selective photodynamic action of UV laser emission. The aim of the present study is to estimate IR and UV absorption and fluorescence spectrum of intact and atherosclerosis-induced changes in aorta and brachiocephalic trunk. Autopsied vessel specimens with artery decease were analyzed. Absorption spectrum of frozen vessel slices (15 micrometers ) and oil emulsion was recorded. Characteristic absorption bands in 3000 cm-1 were noted as for AP as for intact tissue. In 1700 cm-1 AP IR spectrum has an absorption band which is not seen in normal tissue spectrum. Reflection spectrum of intact vessel wall surface and AP at range 45000 to 11000 cm-1 was recorded as well. In 32000 cm-1 reflection was 66% and 43% for AP and intact tissue, respectively. At range 17000 to 13000 cmMIN1 curve position is changed: reflection for AP-66%, for intact wall-93%. Thus, reflection, absorption and fluorescence spectrum of intact and atherosclerotic vessels vary significantly. It provides us with a basis for intravessel examination and selection of laser parameters for harmless endovascular surgery.
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