The study of short-lived induced (singlet-singlet) and long-lived induced (in particular, triplet-triplet) absorption capacity of crystal violet (CV) in various solvents was carried out by the pump-probe method. Water, dimethyl sulfoxide, isopropyl alcohol, and ethyl alcohol were selected as solvents. The formation of triplet states in various CV solvents was revealed upon excitation by nanosecond radiation of the 4th harmonic of a Nd: YAG laser (wavelength 266 nm, average power – 25.5 mV, repetition frequency – 3 Hz, pulse duration – 10 ns, peak power – 10-12 MW/cm2). It is shown that the spectrum of the induced CV absorption in ethanol contains two closely spaced bands at 400 and 485 nm. Short-lived and long-lived induced CV absorption in isopropanol at room temperature (λmax=400 nm) was recorded. Keywords: crystal violet (CV), induced absorption spectra, spectroscopy, pump-probe method.
Results of theoretical research for two psoralen molecules: 8-methoxypsoralen and khellin are presented. Schemes of photophysical processes in psoralens based on quantum chemical calculation by the INDO method are analyzed. The rate constants of intersystem and internal conversions are calculated. We obtained rather high intersystem conversion constant that influences on the fluorescent yield of 8-methoxypsoralen (107 s-1) and an insignificant constant of intersystem conversion for khellin (103 s-1).
The influence of Н2О2 on the degradation of 8-methoxypsoralen (8-MOP) in water-ethanol solutions under the action of KrCl and XeBr excilamp radiation in a photoreactor is investigated. A kinematic model of photodegradation of the investigated molecule is constructed. In water-ethanol solutions the addition of Н2О2 altered the mechanism of decay of 8-MOP under the action of a KrCl excilamp in comparison with irradiation by a XeBr excilamp. This behavior is explained by the fact that the action of 283 nm radiation leads to accumulation of a stable photoproduct. In order to establish the toxicity of this product further research is needed.
The present paper deals with compounds called photosensitizers, namely, psoralen, 3,4-phenyl-4',5'-
cyclohexylpsoralen, 4'-methyl-3,4-cycloheptyl psoralen, 4',5'-dimethyl-3,4-cyclohexyl psoralen (fig. 1). The
absorption spectra from excited triplets states were investigated. The computed triplet-triplet absorption spectra of
research compounds have been determined using INDO method. The experimental triplet-triplet absorption spectra
have been obtained using the technique of laser flash photolysis in ethanol. The compare of computed and experimental
data is shows that the computed second band wavelenght throughout agree very well (0,5-6 nm) with experimental data.
To begin with the present paper deals with compounds called photosensitizers, namely, psoralens (Ps), 21,22-dimethyl-10,11-cyclohexylpsoralen (DCP) and 10,11-phenyl-21,22-cyclohexylpsoralen (PhChP). The absorption spectra from
excited triplets states, photophysical and spectral properties occurring in molecules were investigated in this paper. The
triplet-triplet absorption spectra, spectrum So-Si-absorption and rate constants of Ps, DCP and PhChP have been
determined using INDO method. Experimental absorption spectra of PhCIiP were obtained using CM-2203 spectrofluorimeter.
The present paper deals with compounds called photosensitizers, namely, psoralens (Ps), 4'-hydroxymethyl-4, 5', 8-
trimethyipsoralen (HMTMP) and 10,11-phenyl-21,22-cyclohexylpsoralen (PhChP). The absorption spectra from excited both singlets and triplets states were investigated in this paper. The triplet-triplet and singlet-singlet absorption spectra of PS, HMTMP and PhChP (fig. 1) have been determined using INDO method (see below).
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