Excitation spectra and structure of luminescence centers of manganese ions in single crystals of zinc sulfide

We investigate the photoluminescence excitation spectra in ZnS:Mn single crystals at room temperature and at the temperature of liquid nitrogen with a different concentration of Mn²⁺ ions. The strongest bands peaking at 557, 578, 600, and 637 nm are associated with a different position of the Mn ion in the lattice of the crystals under investigation. The difference obtained in the excitation spectra can be explained by the resonance transfer of energy between the Mn ions. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 67, No. 2, pp. 208–210, March–April, 2000.     

Analysis of the latent structure of luminescence and absorption spectra of thallium complexes

Comprehensive investigations of luminescence, excitation, and absorption spectra as well as of the luminescence kinetics of a frozen LiCl-Tl⁺ solution are carried out. It is established that the luminescence spectrum consists of four components. One component is caused by luminescence of the matrix and the remainder by luminescence of one luminescence center, namely, by the saturated complex of thallium TlCl₂(H₂O)Cl₄. The absorption spectrum consists of three components. Their parameters have been evaluated. Each component of the luminescence spectrum is excited in several components of the absorption spectrum. It is found that the luminescence spectrum components and their intrinsic absorption bands are located differently on the frequency axis. These data are similar to those obtained for other activated solutions of electrolytes. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 67, No. 1, pp. 75–78, January–February, 2000.     

HVPE外延GaN膜中黄带的光致发光激发谱研究

测量了氢化物气相外延方法生长的非特意掺杂和掺碳GaN外延膜的光致发光谱，并在光致发光谱峰位2．25eV(550nm)附近分别测量了光致发光激发谱，对两者进行了比较．从光致发光谱中发现掺碳使黄带明显增强，从光致发光激发谱中看到了掺碳引起的约3．38～2．67eV(367～465nn)范围内的特征激发带．利用CC曲线模型说明了特征激发带和黄带之间的关系，分析了黄带的可能起因．     

氧化锌发光中心的统计力学模型

根据ZnO结构的两种空隙(四面体和多面体),提出了一种发光模型.用统计系综求得了上述两种填隙锌的数量计算公式.     

Spatial structures based on color centers created by electrons in lithium fluoride crystals: Absorption and luminescence characteristics

We have shown that in spatial structures based on color centers created by electrons in a lithium fluoride crystal, the distances between centers reach 1.6 nm and 3.6 nm for F₁ and F₂ centers respectively. This suggests considerable potential opportunities for using electron technology to form structures in the crystals with spatial resolution of such an order of magnitude. We measured the decrease in fluorine content on the irradiated surface of the crystal. We found the concentrations of F₁, F₂, F₃⁺, F₃(R₂), and F₄(N₁) centers. We established that the specific characteristics of color center formation by electrons leads to an increase in the efficiency of creation of F₃ and F₄ centers. We determined the decrease in the average luminescence lifetimes of F₂ and F₃⁺ centers as a result of concentration quenching. We observed distortion of the luminescence contour for F₂ centers as a result of absorption of its short-wavelength portion by other centers and emission of radiation by the latter in its long-wavelength portion. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 75, No. 1, pp. 102–110, January–February, 2008.     

Absorption,fluorescence, and fluorescence excitation spectra of free molecules of indole and its derivatives

We have obtained and analyzed the absorption, fluorescence, and fluorescence excitation spectra of indole vapor, N-acetyl-L-tryptophan vapor, and 3-indole aldehyde vapor. From analysis of the dependence of the fluorescence spectrum of the free indole molecules on the wavelength of the exciting radiation λ_ex, it follows that emission of fluorescence occurs when the molecules undergo a transition from the one electronically excited state ¹L_b. The fluorescence spectra of the studied compounds are insignificantly different, suggesting a major role for the indole chromophore in formation of the compounds. The absorption spectrum of N-acetyl-L-tryptophan, in which the group of atoms is added to the indole ring through a-C-C bond, is similar to the spectrum of indole, while the spectrum of 3-indole aldehyde is significantly different from the indole spectrum due to the effect of the C=O group conjugated with the indole ring. The fluorescence excitation spectra are considerably different from the absorption spectra. This is associated with the strong dependence of the quantum yield for the free molecules on λ_ex. Qualitatively, they are mirror-symmetric to the fluorescence spectra of the stodied compounds. Analysis of the data obtained provides a basis for assuming that in the case of free molecules of indole and its derivatives, the ¹L_a absorption in the extreme long-wavelength region of the spectrum does not overlap ¹L_b absorption. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 74, No. 2, pp. 218–222, March–April, 2007.     

Luminescence and Electrical Properties of CdS Films Doped with Potassium and Sodium

CdS films, both pure and doped with the alkali metals Na and K, with Cl and without it, obtained by the aerosol pyrolysis method from thiourea coordination compounds at a temperature of 250 to 500°C are investigated. The photoluminescence spectra and the dependence of the luminescence intensity on the duration of exposure of samples to a high-power UV radiation have been obtained. The doping of samples results in a tenfold increase in the intensity of the luminescence band in the visible spectrum range (650–850 nm) as compared to pure samples of CdS. Upon irradiation of samples by high-power UV radiation for 1 h, no noticeable change in the intensity of luminescence of CdS films was observed. This is indicative of the stability of the films under study against the action of UV radiation. The luminescent properties of the films, obtained pyrolytically using thiourea coordination complexes, are determined by the synthesis conditions as well as by the chemical nature of the original substances. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 72, No. 4, pp. 509–513, July–August, 2005.     

Method for assigning absorption bands in IR spectra of polyatomic molecules with respect to internal vibrational coordinates

A method is proposed for assigning absorption bands in IR spectra of polyatomic molecules. An algorithm is developed and a Fortran program is written based on this method. The method is illustrated for the example of the toluene molecule. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 74, No. 2, pp. 169–173, March–April, 2007.     

Luminescence centers in thin films of yttrium oxide and yttrium-aluminum garnet activated with bismuth

Luminescence spectra and photoluminescence excitation spectra of Y₂O₃:Bi and Y₃Al₅O₁₂:Bi thin films were investigated. Luminescence was stimulated by the emission from two types of centers that were associated with the substitution of Bi³⁺ for Y³⁺ in sites of the crystal lattice of Y₂O₃ (Y₃Al₅O₁₂) with point symmetries C₂ and C_3i (D₂ and C_3i). The emission of Bi³⁺ in the site with point symmetry C_3i causes blue luminescence in both Y₂O₃:Bi and Y₃Al₅O₁₂:Bi films with maxima at 3.03 eV and 3.15 eV, respectively, that is related to the ³P₁-¹S₀ transition. The emission of Bi³⁺ in the site with point symmetry C₂ gives green luminescence in Y₂O₃:Bi with the maximum at 2.40 eV that is also related to the ³P₁-¹S₀ transition. The emission of Bi³⁺ in the site with point symmetry D₂ leads to ultraviolet luminescence in Y₃Al₅O₁₂:Bi with the maximum at 3.75 eV that corresponds to the ³P₁-¹S₀ transition. The red luminescence band with the maximum at 1.85 eV in Y₂O₃:Bi is due to the presence of structural defects. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 75, No. 2, pp. 202–207, March–April, 2008.     

Vibrational structure of quasiline fluorescence and absorption spectra of bisanthene molecules

The quasiline spectra of the fluorescence and absorption of bisanthene in n-hexane are obtained at 77 and 4.2 K, and their vibration analysis is carried out. Substantial violation of the mirror symmetry of the fluorescence and S₁ ← S₀-absorption bands with respect to both the frequencies and intensities is found. This allowed the conclusion that the S₂-level is localized in the region of vibronic sublevels of the S₁-state with . Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 67, No. 4, pp. 488–491, July–August, 2000.     

Emission and absorption spectra of a Λ type three-level atom driven by a two-mode cavity field with nonlinearities

An analytical expression of the emission and absorption spectra for a Λ type three-level cavity-bound atom interacting with a two-mode cavity field is given using the dressed states of the system. We take into account explicitly the nonlinearities of both the field and the intensity-dependent atom-field coupling. The characteristics of the emission and absorption spectra when one of the two-mode cavity fields is in a binomial state and the other is in a squeezed coherent state are exhibited. The effects of the mean number of photons, detuning, and the kinds of nonlinearities on the spectra are analyzed.     

Normal and pathological color characteristics of human blood components

We have determined the averaged absorption spectra in the near UV and visible regions of the electromagnetic spectrum for aqueous solutions of hemolyzed blood, plasma, and serum from 100 donors and 95 patients with different diagnoses and different severity of their conditions. From the averaged absorption spectra, we calculated the color characteristics of the hemolyzed blood, plasma, and serum from the donors and patients by the standard CIE procedure. The blood is considered as a single, indivisible light-absorbing system in studying complex biological specimens. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 73, No. 2, pp. 220–224, March–April, 2006.     

Dynamic and stationary characteristics of nonlinear luminescence in molecular layers with electronic-excitation energy transfer

We carry out an analysis of the characteristics of nonlinear luminescence of a multicomponent layer system consisting of layers of molecules of a sensitizer, donor, and acceptor with inductive-resonance transfer of energy between the components of the molecular ensemble. We show that in a stationary regime bistable dependences of the populations of excited states of molecules on excitation intensity are realized without external feedback. For pulse pumping, we show the possibility for forming response-luminescence pulses with widely variable characteristics: shape, duration, intensity, and delay. Belorussian State University, 4, F. Skorina Ave., Minsk, 220050, Belarus. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 66, No. 2, pp. 190–196, March–April, 1999.     

Transformation of radiation-induced defects responsible for theF-band of absorption in NaF crystals subjected to irradiation with light and annealing

It has been found that the F-band of optical absorption which is observed in ψ-irradiated NaF crystals consists of three overlapping bands. The band at 345 nm of width 40 nm is independent of the impurity composition of the crystals; it disappears upon exposure to radiation at 345 nm and appears again upon annealing at 460±15 K for 15 min. This band is correlatable in intensity with the superfine structure of an EPR spectrum. The width (65–110 nm) and the spectral position (355–375 nm) of the second band depend on the impurity composition of the crystal. The band of width 90–110 nm at 320–325 nm disappears upon annealing and appears after exposure to light simultaneously with the disappearance of an EPR signal. It is established that the band at 345 nm is caused by quasimolecules based on fluorine atoms, that at 355–375 nm is triggered by F-centers with a different impurity composition near the haloid vacancy, and the band at 320–325 nm owes its appearance to F-centers in a negatively charged state (F′). Institute of Molecular and Atomic Physics, National Academy of Sciences of Belarus, 70 F. Skorina Ave., Minsk, 220072, Belarus. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 66, No. 6, pp. 849–853, November–December, 1999.     

Fe~(24+)离子双电子复合以及和H_2 碰撞的共振转移与激发X射线发射过程的研究

以准相对论Hartree-Fock理论为基础,对Fe~(24+)离子KLn(n=L,M,N,O,P)共振激发态可能辐射衰变通道的双电子复合过程的共振强度进行了系统的理论计算研究,计算了KLL共振激发态谱项能级电偶极允许跃迁的共振强度和截面,在此基础上,根据已有H_2分子的实验Compton轮廓,进一步计算了能量在300—800 MeV范围内,抛射体Fe~(24+)离子俘获H_2分子靶电子的KLn(n=L,M,N,O,P)共振电荷转移与激发X射线发射截面,计算结果与最新实验值或者其他理论计算结果做了对比分析,研究表明,对于Fe~(24+)离子KLn(n=L,M,N,O,P)的双激发态,Kα辐射衰变通道对双电子复合过程的共振强度贡献最大,是起主导性作用的重要通道,Kα辐射衰变X射线的波长范围λ为1.850—1.880A,而非Kα辐射衰变的波长范围λ为1.460—1.601 A,两者共振X射线的波长位置并不重叠。     

Anomalous lateral beam shift and total absorption due to excitation of surface waves in materials with negative refraction

We studied electromagnetic beam reflection from layered structures that include materials with negative refraction. Excitation of leaky surface waves leads to the formation of anomalous lateral shifts in the reflected beams with single or double peak structures. The presence of reasonable losses within material with negative refraction, besides significant influence on manifestation of the giant lateral shifts, can lead to their total suppression and anomalously high absorption of the incident radiation. If, in addition to the resonant excitation of leaky surface waves, radiation inflow exactly compensates their irreversible damping, total absorption of the incoming radiation can be achieved for moderately wide beams.     

Absorption Spectra and Thermostimulated Luminescence of Irradiated KBr Crystals with a High Content of an Na Impurity

The influence of high concentrations of the Na⁺ impurity on the photo and thermostimulated luminescence in an xirradiated KBr crystal has been studied. It is revealed that at an impurity concentration of 1 mol.% the absorption spectrum of the KBr:Na crystal possesses only the bands belonging to the (, I _A) and (F, H _A) pairs of the centers and that the thermoluminescence spectrum consists of two peaks with a maximum at 140 and 165 K.     

Preparation of NaYF4:,Er3+/TiO2 composite and up-conversion luminescence properties under visible light excitation

The up-conversion luminescence composite NaYF 4:Er 3+ /TiO 2 is prepared using the sol-gel method.The specimen has good crystallinity and two shapes,i.e.,viereck and round,while the sizes of viereck and round particles are both micron-sized.The TiO 2 has an anatase structure,while the NaYF 4 has a hexagonal phase,which can be hardly obtained through the common sol-gel method.Due to the big particle size and the high crystallinity of pure NaYF 4:Er 3+,the composite has a small specific surface area that is less than Degussa P25 TiO 2.The NaYF 4:Er 3+ /TiO 2 composite shows several emission peaks at 211,237,and 251 nm under the excitation of 388 nm,at 395 nm and 411 nm under the excitation of 500 nm,and at 467,481,492,and 508 nm under the excitation of 570 nm.