Effect of humic acids on phototransformation of methylphenols in water

We have studied photolysis of a mixture of 2-methylphenol (2-MP) and 4-methylphenol (4-MP) in distilled water and in water containing humic acids. The samples were irradiated under different conditions: by monochromatic light with λ ∼ 222, 283, and 308 nm; by polychromatic light from a mercury lamp in the wavelength region 290–600 nm. We have shown that a mixture of methylphenols is efficiently degraded with irradiation by a KrCl exciplex lamp (λ_rad ∼ 222 nm). Preliminary treatment of peat before extraction of the humic acids has an effect on the extent of photoconversion of the methylphenols. Regardless of the type of humic acids, their presence in solution inhibits photoconversion. The greatest extent of degradation of the methylphenols in aqueous solutions with humic acid additives is detected for irradiation by a KrCl exciplex lamp or a mercury lamp, but it is lower than the extent of degradation of the mixture of methylphenols in water. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 75, No. 4, pp. 577–582, July–August, 2008.     

Luminescence investigations of the degradation of 2-methylphenol and 4-methylphenol in water

Fluorescent characteristics of the photo- and biotransformations of 2-methylphenol, 4-methylphenol and their mixtures in water exposed to uv radiation of various sources and to Penicillium tardum H-2 culture have been studied. The toxicity of these solutions has also been investigated by means of bioluminescent testing. Preliminary exposure of a 4-methylphenol solution (10⁻³ M) to uv radiation with λ ∼ 308 nm or to the radiation of a mercury lamp inhibited the subsequent microbiological degradation. Efficient decomposition of methylphenol molecules in the mixture was detected when it was exposed to the radiation of a mercury lamp or to 222-nm radiation and then subject to biodecomposition. The irradiation of solutions of 2-methylphenol and 4-methylphenol and their low-concentration mixtures with 308-nm uv radiation or with the radiation of a mercury lamp resulted in detoxication of the solutions. Extreme toxicity was shown by 4-methylphenol solutions on exposure to uv radiation with λ ∼ 222 nm. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 12, pp. 88–98, December, 2008.     

Fluorescence and absorption of polystyrene exposed to UV laser radiation

We show that when polystyrene is exposed (for 15–60 sec) to a UV laser light beam (λ = 248 nm), its absorption and luminescent properties change significantly. In the irradiated polymer, optical centers are formed with absorption bands in the 280–460 nm region and fluorescence bands in the 330–520 nm region. We have established the chemical structure of the optical centers for fluorescence of polystyrene. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 73, No. 1, pp. 54–58, January–February, 2006.     

Luminescent analysis of photoinduced detoxification of phenol in the presence of humic substances

We have studied the effect of two detoxifying factors on aqueous solutions of phenol: UV radiation from different sources, and humic substances. The phenol photoconversion processes were monitored by the fluorescent method; the toxicity of the phenol solutions was monitored using a bioluminescence test. It was shown that effective detoxification of an aqueous phenol solution occurs as a result of addition of humic substances; the most effective photoinduced detoxification was detected when using UV radiation from an exciplex lamp (λ_rad = 308 nm). Other UV irradiation sources and the combined action of UV irradiation and humic substances are characterized by a smaller detoxifying effect. In this case, irradiation using an exciplex lamp (λ_rad = 222 nm) increases the toxicity of the phenol solution both in the presence and in the absence of humic substances. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 73, No. 6, pp. 741–745, November–December, 2006.     

Spectroscopic investigation of the plasma of a high-current diffuse discharge in He/Ar/CF2Cl2(CCl4) mixtures

Survey emission spectra in the region of 190–600 nm and time and service-life characteristics of a transverse nanosecond discharge in He/Ar/CF₂Cl₂(CCl₄) mixtures at a pressure of 10–100 kPa are investigated. In the emission spectra, excited products of the decomposition of freons—C₂(A−X), CN(B−X), Cl ₂ ^* , C^*, Cl^*, and Cl^+*— and the emission of ArF at λ=193 nm are revealed. The emissions of Cl ₂ ^* at λ=258 nm and ArF at λ=193 nm were the most intense. The discharge in the He/Ar/CF₂Cl₂ mixture is a multiwave emission source with λ=258 nm Cl ₂ ^* 193 nm ArF, and probably, 175 nm Arcl. It is of interest for applications in UV-VUV-range pulse photometry. The duration of the emission on Cl ₂ ^* , ArF, ArI, ClI, and ClII transitions in the discharge in the Ar/CF₂Cl₂ mixture (P=10–20 kPa) was 200–300 nsec. With adding He and increasing pressure to 100 kPa the duration of the emission decreased by a factor of 1.5–2. The basic mechanisms of the formation of Cl₂, ArF, and CN(B) molecules in the transverse-discharge plasma are considered. Uzhgorod State University, 46, Pidgirna Str., Uzhgorod, 294000, Ukraine. Translated from Zhurnal. Prikladnoi Spektroskopii, Vol. 66, No. 2, pp. 241–246, March–April, 1999.     

Absorption spectra of benzene-isooctane mixtures in the wavelength range 1620–1820 nm

Experimental absorption spectra of benzene, isooctane, and their mixtures are obtained in the wavelength range λ = 1620–1820 nm in which the first overtones of vibrational frequencies of CH, CH₂, and CH₃ hydrocarbon groups are located. Positions of fundamental absorption bands of benzene are refined. Absorption spectra of benzene-isooctane mixtures are shown to intersect in a narrow area near λ ≈ 1695 nm. The main maximum of benzene absorption at λ = 1671.5 ± 0.5 nm, where the influence of isooctane absorption is practically absent, is proposed for determining the content of benzene in benzene-isooctane mixtures. A linear calibration curve for λ = 1671.5 nm that encompasses the full range of benzene concentrations (0–100%) is presented. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 75, No. 5, pp. 631–634, September–October, 2008.     

Luminescent crystals of MIIGa2S4:Er3+ (MII = Eu, Yb, Ca)

We have studied the photoluminescent properties of M^IIGa₂S₄:Er³⁺ polycrystals (M^II = Eu, Yb, Ca) for excitation by radiation with λ = 976 nm as a function of temperature. The samples were obtained by solid-state reaction. We have studied the comparative characteristics of the anti-Stokes and IR luminescence of these luminophores. We have determined the mechanisms for anti-Stokes emission of M^IIGa₂S₄:Er³⁺ crystals. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 74, No. 3, pp. 332–335, May–June, 2007.     

Low-Noise single-frequency He-Ne laser with stable output power at a wavelength of 1.52 µm

The results of investigation of the energy and spectral characteristics of a He-Ne laser (λ_rad=1.52 μm) with transverse microwave discharge are presented. A single-frequency generation mode at a pressure above 6.0 mm Hg was obtained with radiation power 7.0 mW and low level of amplitude noise (10⁻⁵ Hz^−1/2). Active stabilization of the laser power was carried out, which allows reduction in radiation intensity fluctuations from 1–5 to 0.1 %. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 67, No. 1, pp. 127–128, January–February, 2000.     

Luminescence of oxygen molecular ion in neodymium-doped yttria

Pulsed cathodoluminescence spectra of Nd³⁺:Y₂O₃ compacts registered after their annealing in air at a temperature above 950°C exhibit a structured band in the range 610–660 nm with four well-resolved components located at wavelengths of 620.6, 630.6, 645.3, and 655.6 nm. At the same time, the lattice parameter of the cubic yttria increases, and the color of samples changes from light blue to yellowish. In addition, the nearly complete absorption of the intrinsic luminescence band of yttria is observed in the range of 380–600 nm with a center at λ = 485 nm. We assume that these effects are caused by oxygen molecular ions O₂⁻, which are formed in cubic yttria due to the penetration of oxygen into natural anion vacancies. The frequencies of vibrations of the ground and excited states of the oxygen molecular ion has been determined.     

An electron paramagnetic resonance and density-functional theory study on the methyl isotropic hyperfine coupling constants in gamma-irradiated 2,6-di-tert-butyl-4-methylphenol

Single crystal of gammairradiated 2,6-di-tert-butyl-4-methylphenol (BHT) was investigated using an electron paramagnetic resonance (EPR) technique at different orientations in the magnetic field at room temperatures. Taking into consideration the chemical structure and the experimental spectra of the irradiated single crystal of BHT, we assumed that one phenoxyltype paramagnetic species was produced having an unpaired electron localized at the methyl fragment side of the phenyl ring. Depending on this assumption, one possible radical was modeled using the B3LYP/6-311+G(d) level of density-functional theory. EPR parameters were calculated for these modeled radical using the B3LYP/TZVP and B3LYP/EPR-III level. The averaged value of isotropic hydrogen hyperfine coupling constants of rotating methyl functional group of phenoxyl radical is calculated for the first time. Theoretically calculated values of the modeled radical are in reasonably good agreement with the experimental data determined from the spectra (differences in averaged coupling constant values smaller than 5%, and differences in isotropic g values fall into 1 ppt).     

Laser-induced desorption of Na-dimers

We find that Na-dimers are desorbed in a thermal process if rough Na surfaces are irradiated with pulsed laser light of λ=532 nm. In contrast, for light of λ=355 nm, Na₂ can be detached in a non-thermal reaction at low laser fluences. This is concluded from the kinetic energy distributions of the dimers determined by time-of-flight measurements using a second laser at λ=248 nm for photoionization. The transition from non-thermal to thermal desorption at large fluences of the laser light can also be identified. Received: 23 July 1996 / Accepted: 26 August 1996     

Spontaneous parametric light scattering in spatially inhomogeneous nonlinear media based on photonic crystals

The emission spectra of nonlinear media with periodical modulation of the second-order susceptibility that are based on synthetic opals infiltrated by Ba(NO₃)₂, LiIO₃, and KH₂PO₄ are studied using radiation with λ = 400 and 407 nm for excitation. The spectral angular distribution of the emission in the range of 420–650 nm is revealed, as well as the dependence of its spectrum on the photonic stop-band parameters and the exciting radiation characteristics. The emission spectrum of samples with a low dielectric contrast has the shape of a symmetric band with a maximum at 525 nm and a half-width of about 100 nm. The observed emission is interpreted as spontaneous parametric light scattering in a spatially inhomogeneous nonlinear medium.     

Parametrical conversion of the frequency of organic lasers into the middle-IR range of the spectrum

The possibility of parametrical conversion of visible radiation of solid-state organic lasers into the middle-IR range of the spectrum in nonlinear GaSe_1–x S _x (x = 0‒0.13) crystals is investigated. Generation at the difference frequency (wavelength λ₃ = 9.43 μm) of induced oxazine-1 (at λ₁ = 740 nm) and rhodamine-800 (λ₂ = 803.4 nm) radiation is excited. The conversion efficiency is estimated, and prospects for its further increase are demonstrated.     

Effect of polarization and coherence of low-intensity optical radiation on fish embryos

  We have shown that brief exposure of sturgeon embryos (fertilized roe) in the organogenesis stage to low-intensity radiation in the visible region of the spectrum can have a long-term effect on embryonic and post-embryonic development of the fish, detectable 50 days after the irradiation procedure. The biological effects (size-weight characteristics and hardiness parameters of the fish relative to unfavorable habitat conditions) induced by linearly polarized emission from a monochromatic laser source (helium-neon laser, λ = 632.8 nm, Δλ ≈ 0.02 nm) and a quasi-monochromatic light-emitting diode (LED) source (maximum in emission spectrum λ = 631 nm, Δ λ = 15 nm) are practically the same. Going to broadband linearly polarized radiation (λ = 420–800 nm) is accompanied by a decrease in the biological effect. From the results of studies of the effect on embryos from linearly polarized and unpolarized radiation from an LED source and also the effect of linearly polarized, circularly polarized, and unpolarized radiation from a helium-neon laser, we concluded that the type of polarization is of critical importance in realization of the biological effect of radiation. In this case, the maximum stimulating effect (on the size×weight characteristics and the hardiness parameters for juvenile fish) is observed on exposure to linearly polarized radiation; the photobiological effect induced in the same dose range by light with natural polarization (i.e., unpolarized) is significantly less pronounced; the stimulating effect of circularly polarized radiation occupies an intermediate position. Based on the presented data and also on data obtained previously, we conclude that among the resonant and nonresonant photophysical processes (orientational effect of light, effect of gradient forces, dipole-dipole interactions, thermooptic processes) capable of inducing photobiological effects dependent on such laser-specific characteristics as polarization and coherence, the determining influence in the processes studied in this work comes from the orientational effect of light and dipole×dipole interactions. And the orientational effect can appear for anisotropic media with liquid-crystal type ordering (especially domains in membranes and multiple-enzyme complexes) both under conditions when there is no resonant absorption and for weakly absorbing structures, and can initiate a change in their conformations and accordingly their functional characteristics. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 75, No. 6, pp. 843–858, November–December, 2008.     

Structure and absorption spectra of substituted 2-hydroxy-2-trifluoromethylchroman-4-ones

UV absorption spectra of substituted 2-hydroxy-2-trifluoromethylchroman-4-ones (chromanones) in aqueous ethyleneglycol were studied. Replacement of hydrogen in the aromatic ring of the chromanones by CH₃ or CF₃ groups was shown to cause the molar extinction coefficients of the K, B, and C=O bands to shift from 16,160 to 27,980 and 30,250 dm³/mol·cm; from 12,750 to 17,920 and 16,130 dm³/mol·cm; and from 3850 to 3630 and 2760 dm³/mol·cm, respectively. Increasing the solution pH from 1 to 10.5 affected weakly the aromatic ring bands yet impacted greatly the chromanone carbonyl bands, causing their λ_max to shift from 311–326 nm to 342–346 nm and their extinction coefficients to increase from 2760–3850 dm³/mol·cm to 9940–10,160 dm³/mol·cm. A further rise in the pH resulted in hypochromia of the carbonyl band due to the destruction of the chromanones. The results were confirmed by NMR spectroscopy and GC methods.     

Continuous frequency up-conversion in a double-Λ scheme of Na2

 In a double-Λ level configuration of Na₂ molecules, involving rotational–vibrational levels of the X, A and B bands, continuous resonant frequency mixing ω₄=ω₁−ω₂+ω₃ is demonstrated. A DCM dye laser at 661 nm (λ₁) pumps a molecular Raman laser at 746 nm (λ₂) in a sodium heatpipe, which is used to generate the molecular vapour. In the same heatpipe, both fields are mixed with the radiation of an argon-ion laser at 514 nm (λ₃) to generate up-converted laser radiation at 473 nm (λ₄). For laser powers of 200 mW (λ₁), 700 mW (λ₂, internal power) and 140 mW (λ₃), an output power of 120 μW (λ₄) has been achieved. Dependences of the generated radiation on the pump fields (powers and detunings) and polarization features are presented; influences of coherent coupling and population transfer mechanisms are discussed. Received: 7 October 1996     

Preparation, structures and photoluminescent enhancement effect of PbWO4–TiO2 composite nanofilms

A novel route for preparing PbWO₄–TiO₂ nanofilms on a glass substrate is firstly proposed. The collodion is used as a dispersant and film-forming agent. The nanofilms are characterized through SEM, XRD, TG/DTA, PL and IR, respectively. The results of XRD indicate PbWO₄ particles with tetragonal scheelite structure and TiO₂ particles with Anatase phase, and SEM shows they are well dispersed in the substrate. Compared with nanoparticles, when TiO₂ nanoparticles are added in 5% ratio, the PL intensities at 395 nm of PbWO₄ nanofilms are enhanced obviously. IR spectrum reveals a large absorption band between 750 and 870 cm⁻¹, which is the W–O stretching vibration in WO₄ tetrahedron.     

Investigations into the spectral and luminescent properties of methylphenols in neutral and ionic forms in aqueous micelle solutions

The special features of the absorption and fluorescence spectra of some substituted phenols (2-, 4-methylphenol and 2-amino-4-methylphenol) in aqueous micelle solutions are investigated on addition of an alkali and acid. A fluorescence band of 4-methylphenol in the anion form is detected in the presence of a cation surfactant. The fluorescence efficiency of 4-methylphenol in the presence of the triton X100 micelle decreases in comparison with aqueous solutions. It is established that the quantum yield of fluorescence of 2-methylphenol in the presence of N-cetyltrimethyl ammonium bromide (CTAB) increases in comparison with the aqueous solution (ϕ_fl = 0.25 and 0.17, respectively). The constant of fluorescence quenching for methylphenol in aqueous micelle solutions by the alkali is two orders of magnitude higher than by the acid. The proton-acceptor properties of 2-amino-4-methylphenol are higher than of 4-methylphenol. __________ Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 11, pp. 54–61, November, 2005.     

Lasing of a DCM dye layer in carbazole-based films

We have studied the spectral and lasing properties of 4-dicyanomethylene-2-methyl-6-(p-dimethylaminostyryl)-4H-pyran (DCM) in polyepoxypropylcarbazole (PEPK), polybutylcarbazole (PBK), and polyvinylcarbazole (PVK) films when excited by emission from a XeCl laser (λ = 308 nm) and the second harmonic of a YAGNd laser (λ = 532 nm). Stimulated emission was excited without an external cavity in the traveling wave mode in films of thickness 0.5–0.8 μm, obtained by the centrifuging method. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 73, No. 2, pp. 177–181, March–April, 2006.     

Spectrofluorimetric methods of stability-indicating assay of certain drugs affecting the cardiovascular system

Two stability-indicating spectrofluorimetric methods have been developed for the determination of ezetimibe and olmesartan medoxomil, drugs affecting the cardiovascular system, and validated in the presence of their degradation products. The first method, for ezetimibe, is based on an oxidative coupling reaction of ezetimibe with 3-methylbenzothiazolin-2-one hydrazone hydrochloride in the presence of cerium (IV) ammonium sulfate in an acidic medium. The quenching effect of ezetimibe on the fluorescence of excess cerous ions is measured at the emission wavelength, λ_em, of 345 nm with the excitation wavelength, λ_ex, of 296 nm. Factors affecting the reaction were carefully studied and optimized. The second method, for olmesartan medoxomil, is based on measuring the native fluorescence intensity of olmesartan medoxomil in methanol at λ_em = 360 nm with λ_ex = 286 nm. Regression plots revealed good linear relationships in the assay limits of 10–120 and 8–112 g/ml for ezetimibe and olmesartan medoxomil, respectively. The validity of the methods was assessed according to the United States Pharmacopeya guidelines. Statistical analysis of the results exposed good Student’s t-test and F-ratio values. The introduced methods were successfully applied to the analysis of ezetimibe and olmesartan medoxomil in drug substances and drug products as well as in the presence of their degradation products.