共查询到20条相似文献,搜索用时 15 毫秒
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V. A. Svetlichnyi M. P. Samtsov O. K. Bazyl’ O. V. Smirnov D. G. Mel’nikov A. P. Lugovskii 《Journal of Applied Spectroscopy》2007,74(4):524-532
We present results of experimental and theoretical studies of the optical characteristics of a new indotricarbocyanine dye
that is capable of effectively limiting the power of laser radiation in the visible spectral range. The spectral-luminescent
and energy characteristics of the dye molecules and their absorption spectra from the excited state with nanosecond resolution
are investigated experimentally. Quantum-chemical methods are used to calculate electronic absorption spectra from the ground
(S0 → Sn) and excited (S1 → Sn) states and to determine the nature of electronic states of the molecule and the rate constants of intramolecular photophysical
processes. The results of the theoretical research agree with experimental data. It is shown that the investigated dye has
singlet-singlet absorption at 400–600 nm. Nonlinear absorption of the dye upon excitation by radiation of the second harmonic
of a Nd:YAG laser is studied by z-scanning with an open diaphragm. The ratio of dye absorption cross sections from the excited
and ground states at 532 nm is determined in the framework of a three-level model. The results are compared with those for
previously studied compounds.
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Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 74, No. 4, pp. 473–480, July–August, 2007. 相似文献
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Starting from conventional rate equations describing the multimode operation of a laser with a broad homogeneous emission line, a system of approximately valid equations, suitable for both analytical and numerical studies of the spectral properties of laser radiation not too far from threshold, has been derived by introducing equations of motion for the spatial Fourier components of the inversion densityN(z, t), thus replacing the equation of motion forN(z, t) itself. Analytical solutions for steady-state operation were found and physically discussed in the following cases: (a) ring laser, (b) jet-stream laser with the active medium positioned either near one of the (Fabry-Perot) resonator mirrors or in the centre of the resonator, and (c) laser with a Fabry-Perot resonator completely filled with the active medium. The spectra thus calculated indicate that spatial hole burning is most efficient in providing mode co-existence in configuration (c), where it gives rise to a significant bandwidth. It is of minor importance, however, in case (b), where the spectrum differs only slightly from that of a ring laser, which is clearly free from hole-burning effects. 相似文献
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M. P. Samtsov E. S. Voropay L. S. Liashenka D. G. Melnikau K. N. Kapleusky A. P. Lugovskij 《Journal of Applied Spectroscopy》2011,78(1):110-116
We present the results for studies of the spectral luminescence properties of a symmetric indotricarbocyanine dye (PD1) in HeLa tumor cells and animal tissues in vivo during a photochemotherapy session and after the end of the session. We have established that when the dye is exposed to light in tumor tissues, changes occur in the position and half-width of the dye fluorescence spectra, while in a culture of HeLa cells its spectral characteristics are constant. Based on analysis of the effect of overlap between the absorption spectra of endogenous biomolecules and the fluorescence spectra of the dye plus comparison of the experimental data with numerical modeling results, we have concluded that the observed changes in the fluorescence spectra of PD1 in vivo are due to a change in the ratio of the different forms of hemoglobin in the tumor tissue. We have shown that the spectral characteristics of PD1, fluorescing in the near IR range, correlate with the depth of tumor tissue necrosis achieved on exposure to light. We have established that tumor tissue necrosis occurs down to a depth of 2 cm in the case of all strains studied: S-45, SM-1, and W-256, where as a result of exposure to light, we observe an increase in the half-width and a short-wavelength shift of the fluorescence spectrum of the dye PD1, and also the intensity of its fluorescence does not recover. 相似文献
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P. P. Pershukevich I. K. Shushkevich E. A. Makarova K. N. Solov’eva 《Journal of Applied Spectroscopy》2008,75(5):706-713
We have studied the spectral luminescence properties of a zinc complex of dibenzobarreleno-substituted tetraazaisobacteriochlorin
(a synthetic tetrapyrrole pigment which is the structural analog of the biologically important chromophore isobacteriochlorin)
and a palladium complex of dibenzobarreleno-substituted tetraazachlorin. We have shown that despite the substantial effect
of aza-substitution on the electronic structure and the electronic spectra of the tetrapyrrole molecules, the effect of hydrogenation
of adjacent pyrrole rings on the spectral luminescence properties is similar in compounds with nitrogen and carbon bridges.
As in the free base case, the fluorescence of the studied zinc complex is strongly quenched at 293 K but flares up at 77 K
(temperature and viscosity-dependent quenching). To study the substituted Zn-tetraazaisobacteriochlorin, we determined the
position of the 0-0 band of the low-intensity transition S0 → S2 and showed that the S2 → S1 energy difference increases with bridge aza substitution. For the Pd complex of dibenzobarreleno-substituted tetraazachlorin,
we could not detect phosphorescence in the near IR region (to 1150 nm); we detected weak fluorescence.
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 75, No. 5, pp. 700–707, September–October, 2008. 相似文献
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S. N. Letuta V. S. Maryakhina S. N. Pashkevich R. R. Rakhmatullin 《Optics and Spectroscopy》2011,110(1):67-70
We studied the kinetics of delayed fluorescence and phosphoresce of exogenous fluorophores in cells extracted from tumorous
and normal tissues of the mammary gland of mice of the BYRB strain. We revealed the specifics and determined regularities
of the kinetics of long-term luminescence of fluorophores in different cells. The possibility of developing of a method for
the early fluorescence diagnostics of the pathology of biotissues based on the obtained results is discussed. 相似文献
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M. P. Samtsov S. A. Tikhomirov O. V. Buganov K. N Kaplevsky D. G. Melnikov L. S. Lyashenko 《Journal of Applied Spectroscopy》2009,76(6):783-790
Spectral-kinetic and photochemical properties of HITC dye with iodide and perchlorate counterions have been studied in environments
where the dye molecules exist in different ionic forms. In ethanol, the dye molecules exist as free ions; in dichlorobenzene,
as contact ion pairs. Superfast transformation of non-stationary spectra in an HITC dye bleaching band is found. The observed
effects are interpreted within the framework of concepts on “burning out” a notch in the contour of a non-uniformly widened
vibronic band of S
0 → S
1-absorption. Qualitative differences in recorded absorption spectra from the dye excited electronic states for weakly and
highly polar solvents are found. It is shown that the observed differences are caused by superfast charge transfer in the
contact ion pairs that results in the formation of free radicals. 相似文献
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Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 54, No. 4, pp. 605–610, April, 1991. 相似文献
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Complex Ce4+-Nd3+ centers were formed in silica gel-glasses. These centers were characterized by weak cross-relaxation quenching of luminescence; an increased luminescence branching ratio in the 4F3/2→4I11/2, 4I13/2 transitions; strong structuring of the analogous spectral bands; and effective intracenter sensitization of luminescence. On reducing the Ce4+ ions to the triply charged state, the structure of the luminescence bands of Nd3+ ions became weaker and the ratio of their intensities approached the value typical of an Nd-containing silica gel-glass. 相似文献
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S. I. Drapak 《Technical Physics》2007,52(8):1036-1039
The photoluminescence intensity of an alcoholic solution of propolis at room temperature is studied as a function of the propolis concentration. It is found that, unlike in most organic substances and complex compounds (including natural bee honey), where luminescence is maximal at a certain solute-to-solvent ratio, the luminescence intensity increases with the concentration of propolis and is maximal in elastic solid films. Variation of the film’s temperature in the range from 520 to 570 K causes neither a shift of the fundamental absorption edge nor a qualitative change in the photoluminescence spectrum (E max = 2.9 eV at T = 300 K) but leads to a decrease in the luminescence intensity. This effect may be due to the disturbance of molecular order in the films under study. It is inferred that propolis deserves attention as a promising optoelectronic material. 相似文献
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V. I. Kochubey T. V. Kulyabina V. V. Tuchin G. B. Altshuler 《Optics and Spectroscopy》2005,99(4):560-566
The changes in the absorption spectra of solutions of Indocyanine Green are studied in relation to the nature and composition of the solvent and the dye concentration. The reflection spectra from selected areas of human skin stained with different solutions of Indocyanine Green are studied in vivo upon successive stripping of stained surface epidermal layers. The reflection spectra from human hairs stained in vitro with an alcohol solution of Indocyanine Green are measured. It is shown that the shift of the absorption band maximum of Indocyanine Green determined by the interaction of the dye with epidermal or hair keratin does not depend on the solvent composition or the depth of location of the stained layer. 相似文献
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V. A. Aseev V. V. Golubkov A. V. Klementeva E. V. Kolobkova N. V. Nikonorov 《Optics and Spectroscopy》2009,106(5):691-696
Transparent nanoglassceramics has been synthesized based on lead fluoride silicate glass doped with erbium ions. It is shown that heat treatment of lead fluoride silicate glass leads to the formation of nanoscale (16–40 nm) crystalline phase of lead fluoride. X-ray diffraction analysis and measurement of spectral luminescence properties have revealed that the erbium ions enter the crystalline phase of lead fluoride. 相似文献
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Spectral and luminescence properties of gadolinium gallium garnet epitaxial films doped with terbium
N. V. Vasil’eva V. V. Randoshkin V. N. Kolobanov E. B. Kryukova V. V. Mikhaĭlin N. N. Petrovnin V. G. Plotnichenko Yu. N. Pyrkov D. A. Spasskiĭ N. N. Sysoev 《Physics of the Solid State》2007,49(3):478-483
Gadolinium gallium garnet single-crystal films containing terbium are grown through liquid-phase epitaxy from a supercooled solution melt in the PbO-B2O3 system. The optical absorption spectra in the wavelength range 0.2–10.0 μm and the luminescence spectra excited by synchrotron radiation with energies in the range 3.5–30.0 eV are investigated at temperatures of 10 and 300 K. It is revealed that the optical absorption spectra contain an absorption band with the maximum at a wavelength λ ≈0.260 μm, which corresponds to the spin-allowed electric dipole transition between the electronic configurations 4f 8(7 F 6) → 4f 7(8 S)5d of the Tb3+ ions. The narrow low-intensity absorption bands attributed to the 4f → 4f transitions from the 7 F 6 ground level to the 7 F 0–5 multiplet levels of the Tb3+ ions are observed in the wavelength range 1.7–10.0 μm. In the luminescence spectra measured at a temperature of 10 K, the highest intensity is observed for a band with the maximum at a wavelength λ ≈ 0.544 μm, which is associated with the 5 D 4 → 7 F 5 radiative transition in the Tb3+ ion. 相似文献
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Heat transport properties within living biological tissues with temperature-dependent thermal properties 下载免费PDF全文
Ying-Ze Wang 《中国物理 B》2023,32(1):14401-014401
Understanding of the heat transport within living biological tissues is crucial to effective heat treatments. The heat transport properties of living biological tissues with temperature-dependent properties are explored in this paper. Taking into account of variable physical properties, the governing equation of temperature is first derived in the context of the dual-phase-lags model (DPL). An effective method, according to the Laplace transform and a linearization technique, is then employed to solve this nonlinear governing equation. The temperature distribution of a biological tissue exposed to a pulsed heat flux on its exterior boundary, which frequently happens in various heat treatments, is predicted and analyzed. The results state that a lower temperature can be predicted when temperature dependence is considered in the heating process. The contributions of key thermal parameters are different and dependent on the ratio of phase lag and the amplitude of the exterior pulsed heat flux. 相似文献