Brief review of the data on the color centers, which are formed in the near-cluster regions of LiF, NaF and MgF2 nanocrystals, is presented in this paper. The wavelengths of the maxima and half widths of the absorption and photoluminescence bands, photoluminescence lifetimes, the values of the Huang-Rhys parameters, the wavelengths of zero-phonon lines for the bulk and near-cluster color centers in LiF, NaF and MgF2 are given.

We study the silica gel-glasses obtained by vitrification in air or in a gas mixture of H 2 :Ar xerogels doped with Sm, Al, and Ba. It is found that during their synthesis it is possible to form impurity hexagonal and tetragonal crystallites of SiO 2 and tetragonal crystallites of SmSi 2 . When the reducing synthesis conditions are applied, the incorporation of samarium in glass simultaneously in two oxidation states (3+ and 2+) takes place. Meanwhile, Sm-Al-containing glasses provide a sufficiently effective sensitization of the luminescence of Sm 2+ ions by Sm 3+ ions, while in Sm-Al-Ва-containing glasses this effect is absent because Sm 2+ ions are localized mainly in the glass sublattice formed with the participation of Ba 2+ ions. Based on the spectra obtained, the positions of the energy states of the Sm 2+ and Sm 3+ ions in such glasses are calculated.

The luminescence and absorption properties of LiF, NaF and MgF2 nanocrystals containing radiation-induced point defects with new properties are investigated. The influence of temperature, at which nanocrystals are maintained after their manufacture, on the efficiency and kinetics of such defects formation is examined. For LiF samples, the activation energy of fotmation processes is determined. X-ray diffraction reflections are compared for LiF nanocrystals, unannealed and annealed after fabrication, unannealed and irradiated with γ-rays or electrons, as well as those manufactured by fragmentation of an irradiated crystal plate. Conclusions are drawn about the processes of self-assembled nanostructures formation, the presence of which is a prerequisite for the creation of radiation-induced point defects with new properties.

The results are presented of a study of the photoluminescent (PL) properties of an undoped porous anodic alumina (PAA) and PAA doped with manganese ions. The PAA samples were prepared by anodization of aluminum. The effect of annealing conditions in vacuum on the PL spectra was studied for the first time and a comparative analysis was made with the spectra of the PAA annealed in air. Vacuum annealing was used to obtain oxygen-deficient alumina. A strong dependence of the PAA PL intensity on the annealing temperature in vacuum has been found: for the samples annealed at 600°С, the PL intensity is 15 times higher than that measured on the initial samples, whereas for the samples annealed in air it increases only 4.5-fold with excitation at the wavelengths of 275 nm. This is the result of the formation of a high concentration of oxygen vacancies during annealing in vacuum under conditions of oxygen deficiency as compared with the samples annealed in air, where diffusion of oxygen from air leads to a decrease in vacancies. A significant increase in the PL intensity permits consideration of the vacuum-annealed PAA as a promising material for dosimetry.

The fifth author's name should read K. N. Nishchev. Figure 3 on page 587 is incorrect.

Changes in the concentrations of ordinary radiation defects and formation of near-cluster radiation defects (color centers) are shown to occur in nanocrystals fabricated by mechanical fragmentation of irradiated LiF crystals. Concentrations of near-cluster color centers increase to a steady value after fragmentation and remain constant at room temperature for a long time. UV irradiation of fabricated nanocrystals after termination of center formation processes in them causes the concentration of near-cluster defects containing three anion vacancies and two electrons to increase significantly. It is demonstrated that there are single-vacancy color centers as well as ordinary and near-cluster aggregate centers in unirradiated nanocrystals fabricated by fragmentation of unirradiated crystals.

Nanocrystals of magnesium fluoride have been irradiated by gamma-rays at 77 K or electrons at room temperature. Three types of radiation-induced defects (color centers) with previously unknown characteristics, such as luminescence and excitation luminescence spectra, luminescence lifetime, and Huang-Rhys parameters, have been observed and studied in these nanocrystals. It has been established that the luminescence excitation spectra of these centers contain two closely spaced bands with slightly different intensities. It was shown that pre-irradiation annealing of nanocrystals at temperatures above 823 K for one hour leads to the impossibility of observing all three new types defects in irradiated samples. It has been found that during the post-radiation annealing of samples, one of the new types of color centers is transformed into a well-known defect described earlier in the literature. It is concluded that new types of defects are generated near the nanoclusters which are formed during nanocrystals production. It has been found that defects previously known and referred to as M (C-1) consist of two modifications which differ in luminescence and excitation luminescence spectra, and in dependencies of their concentrations upon temperature annealing.

The possibility of formation of radiation defects with new luminescent properties is investigated in sodium and magnesium fluorides nanosized crystals. Nanocrystals obtained by mechanical fragmentation of the single crystals have been irradiated by gamma-rays at 77 K or electron beams at room temperature. Their TEM images have been received. Luminescence, luminescence excitation and absorption spectra of nanocrystals have been measured immediately after.-irradiation without samples defrosting and after termination of the defects aggregation processes at room temperature. The formation of radiation color centers with previously unknown optical characteristics has been discovered in nanocrystals. Numbers of anion vacancies and electrons entering into these centers composition were established in sodium fluoride. The structure transformation of the centers, containing two anion vacancies and an electron, was revealed after sodium fluoride samples defrosting. For sodium fluoride the data on the Huang-Rhys parameters and lifetimes of the photoluminescence for here studied and previously known centers of the same composition are determined and compared. The results obtained show that near-clusters color centers can be formed in crystals with different structures and atomic compositions.

hould read “porphyrazine” instead of “porphyrazin”; should read “intersystem crossing” instead of “intercombinational conversion”; should read “mirror-symmetrical” instead of “reflection-symmetric”; should read “fluorescence enhancement” instead of “fluorescence buildup.” Page 722, Abstract, lines 9–10 from the top, the sentence should read: This characteristic increases upon tetrapyrrole phenylation. Page 727, left column, lines 17–18 from the top, the sentence should read: The vibronic transition parts of the emission spectrum are diffuse, (…) Page 727, left column, lines 29–30 from the top, the sentence should read: Note that the Stokes shift in these cases is relatively large. Page 729, left column, lines 8–10 from the bottom, the sentence should read: For H 2 Ph 8 TAC mp and H 2 Ph 6 TAC tm , the enhancement of fluorescence is weaker than in the former case: on cooling, τ F is increased by a factor of 4–5 in MTHF and by a factor of only 2.6–3 in toluene. Page 729, right column, lines 9–10 from the footnote, the sentence should read: It is seen from Table 1 that our results agree reasonably well with previously reported data. Page 730, left column, lines 16–19 from the top, the sentence should read: The lifetime for the outgassed H 2 TAP solution in toluene (τ T 0 ) was measured by A.S. Stasheuski as phosphorescence decay at λ reg = 1070 nm using the setup described in [29]. Page 730, left column, lines 20–23 from the top, the sentence should read: The τ T value derived from the kinetics of the rise of singlet oxygen luminescence [26] for the nonoutgassed solution at λ reg = 1272 nm is 162 ns; Page 730, right column, lines 25–27 from the top, the sentence should read: Therefore, for H 2 TAP (λ F 00 ≈ 620 nm), the internal conversion probability should not be high. Page 731, left column, the heading of Table 2 should read: Bond lengths in the porphine macrocycle (Å). Page 731, left column, lines 3–6 from the top, the sentence should read: For elucidating the mechanism of the deactivation of the S 1 state, it was of essential interest to see whether the enhancement of H 2 TAP fluorescence would be observed at 77 K. Page 733, left column, lines 2–3 from the top, the sentence should read: The corresponding difference for the H 2 P–H 2 C pair is 0.013 Å. Page 733, left column, lines 14–16 from the top, the sentence should read: The macrocycle undergoes additional contraction, and the symmetry of its conjugated system is very close to D 2h . Page 733, right column, line 21 from the top should read: Replacement of the methine bridges (…) Page 734, left column, lines 8–11 from the figure caption, the sentence should read: This is the main reason of the large bathochromic shift of the Soret band of H 2 Ph 8 TAP and MgPh 8 TAP [16] relative to H 2 TAP and MgTAP, respectively. Page 734, left column, lines 1–4 from the bottom, the sentence should read: The complete INDO/Sm calculation yields the corresponding quantitative characteristics, which are in good agreement with experimental data (see below). Page 740, left column, reference no. 25 should read: 25. V. A. Galievsky, A. S. Stasheuski, V. V. Kiselyov, A. I. Shabusov, M. V. Belkov, and B. M. Dzhagarov, Instrum. Exp. Tech. 53, 568 (2010). 25. V. A. Galievsky, A. S. Stasheuski, V. V. Kiselyov, A. I. Shabusov, M. V. Belkov, and B. M. Dzhagarov, Instrum. Exp. Tech. 53 , 568 (2010). 30. V. L. Ermolaev and E. B. Sveshnikova, Acta Phys. Pol. 34 , 771 (1968).

Near-surface color centers in sodium fluoride nanocrystals have been formed. At pre-irradiation annealing of sodium and lithium fluorides samples at temperatures of 623 K and above, the near-surface color centers in them have not been found after gamma-irradiation. Annealing lithium fluoride nanocrystals with the near-surface defects leads to their transformation into bulk ones of the same composition.

The results are presented of a comparative study of photoluminescent (PL) properties of unalloyed and Mn-alloyed porous anodic alumina (PAA) subjected to annealing at temperatures in the range of Тa=200–1300°С. The possibility of alloying of PAA with metal atoms is illustrated through an example of Mn atoms, and the effect of this impurity on the optical properties of aluminum oxide is examined. Alloying of PAA with Mn ions leads to the formation of complex defects including manganese ions and oxygen vacancies. The difference observed in the spectral dependences of the PL intensity of alloyed and unalloyed specimens is explained by the change in the valence of manganese ions in the complex defects. A decrease has been discovered in the PL intensity of the PL bands and R-lines of Mn and Cr ions in the α-phase under prolonged UV-exposure of the alloyed samples.

Dynamic and static quenching of 6-(2′,7′-dimethoxy-4′,5′-dichloro)carboxyfluorescein (JOE) by nucleosides (deoxyadenosine, deoxycytidine, deoxyguanosine, thymidine, and deoxyuridine) in Tris-acetate buffer solution was analyzed using the Stern–Volmer equation. Only one of the five nucleosides, deoxyguanosine, exhibited predominantly static quenching. The fluorescence quantum yields in buffer solution of 5- and 6-carboxyfluorescein (FAM) and 5-and 6-JOE bound covalently to the oligonucleotide by a rigid linker (4-trans-aminocyclohexanol) were greater than those of their analogs with a flexible linker (6-aminohexanol). It was shown that fluorescence quenching in systems with a flexible linker occurred mainly through van-der-Waals contact of the fluorophore with guanine. An increase in the number of consecutively located guanines in the oligonucleotides and their duplexes bound to the dye by a linker decreased the fluorescence quantum yield. Quantum-chemical calculations using the Gaussian 09 program provided an interpretation for the low-frequency shifts of 5-FAM and 5-JOE absorption and fluorescence spectra relative to those of the 6-isomers.

Influence of pre-irradiation annealing temperature on the efficiency of the subsurface color center formation in γ-irradiated lithium fluoride nanocrystals has been studied. Increase of the annealing temperature reduces the efficiency of formation of these centers. Nanocrystals lose their ability to form subsurface color centers after pre-irradiation annealing at 623 K and higher temperatures. The formed subsurface color centers are partially transformed into the usual centers of the same composition during the post-radiation annealing at certain temperatures. It has been shown that the mechanical fragmentation of lithium fluoride crystals leads to the formation of nanosized clusters in their subsurface layer. Subsurface radiation color centers which are located near the clusters are subjected to the modified crystal field. This circumstance causes strong differences between the luminescent characteristics of subsurface color centers and usual centers of the same composition in the crystal bulk, where there are no clusters. The clusters are completely destroyed after annealing the samples at 623 K and higher temperatures. The obtained results indicate that the presence of nanoclusters is a prerequisite for the formation of subsurface radiation color centers with specific fluorescent properties. The thickness of the subsurface layer, where subsurface color centers can be formed, has been estimated.

It is shown that surface color centers of the same type are formed in the surface layer and in regions with damaged crystal structure inside crystalline lithium fluoride after γ-irradiation. Results are presented from a study of the effect of pre-irradiation annealing on the efficiency with which surface centers are formed in lithium fluoride nanocrystals. Raising the temperature for pre-irradiation annealing from room temperature to 250°C leads to a substantial reduction in the efficiency with which these centers are created. Surface color centers are not detected after γ-irradiation for pre-irradiation annealing temperatures of 300°C and above. Adsorption of atmospheric gases on the crystal surface cannot be regarded as a necessary condition for the formation of radiation-induced surface centers.

The spectral and polarization characteristics of optically anisotropic polyvinyl alcohol (PVA) films containing 4,4'-bis[4-(phenylamino)-6-(methoxy-1,3,5-triazin-2-yl)amino]stilbene-2,2'-disulfonic acid as dichroic dye, which has intense blue fluorescence, were investigated by polarized luminescence and absorptionspectroscopy in the IR and UV regions. With fourfold uniaxial stretching of the film the orientation parameter of the dye amounts to 0.82–0.86, the maximum polarizing ability of the film is 96% (at the maximum of the absorption band at 375 nm), and the degree of polarization and quantum yield of fluorescence at the optimum concentration of the dye amount to 0.90 and 0.91. The degree of orientation of the dye molecules depends weakly on the concentration (0.01–0.50 wt.%) and increases with increase of the uniaxial stretching of the film. The insertion of the dye molecules between the PVA chains leads to a reduction of the crystallinity of the polymeric matrix.

Lithium fluoride nanocrystals were irradiated by gamma rays at a temperature below the temperature corresponding to the mobility of anion vacancies. The kinetics of the aggregation of radiation-induced defects in subsurface layers of nanocrystals during annealing after irradiation was elucidated. The processes that could be used to determine the activation energy of the diffusion of anion vacancies were revealed. The value of this energy in subsurface layers was obtained. For subsurface layers, the concentrations ratio of vacancies and defects consisting of one vacancy and two electrons was found. The factors responsible for the differences in the values of the activation energies and concentration ratios in subsurface layers and in the bulk of the crystals were discussed.

We have used a colloidal chemical method to synthesize ultradisperse powders of lutetium aluminum garnet activated by Ce3+ ions. We used optical spectroscopy, x-ray and neutron diffraction to study their spectral luminescence and structural properties as a function of the activator concentration and the heat treatment conditions for the precursor. We have observed a change in a number of structural parameters of these powders, due to the particular details of their synthesis, which leads to distortion of the crystallographic environment of the Ce3+ ions and a change in the intensity of their luminescence. We show that among the studied powders, the highest integrated luminescence intensity is observed for an activator concentration of 1.0 at.%, and its maximum is achieved with heat treatment in the range 1200–1300°C.

With the aim of obtaining new fluorescent biomarkers, we have synthesized nanodiamond–dye dyads which form a stable aqueous suspension. In the dyads, by means of nucleophilic substitution of the nitro group, the N-substituted 4-nitro-1,8-naphthalimide was added to the ultradisperse nanodiamonds via a long alkyl chain. We studied the absorption and fluorescence spectra and also the fluorescence decay kinetics for the dyads. We propose that the non-exponential fluorescence decay for the dyads in aqueous suspension is due to two ways to position the plane of the N-substituted 1,8-naphthalimide relative to the plane of the nanodiamond.

Isobestic and isoemission points are recorded in the combined absorption and luminescence spectra of two types of radiation defects involved in complex processes consisting of several simultaneous parallel and sequential reactions. These points are observed if a constant sum of two terms, each formed by the product of the concentration of the corresponding defect and a characteristic integral coefficient associated with it, is conserved. The complicated processes involved in the transformation of radiation defects in lithium fluoride are studied using these points. It is found that the ratio of the changes in the concentrations of one of the components and the reaction product remains constant in the course of several simultaneous reactions.

One well established class of nanomaterials is based on colloidal core/shell CdSe/ZnS quantum dots (QDs). Capping organic shells (including surfactants and ligands) have considerable impact on the surface structure, optical properties and exciton relaxation in QDs as has been successfully studied experimentally and theoretically for several systems [1–3]. Ensemble experiments on QDs are hampered by the fact that it is not immediately obvious whether an identified variation of parameters (such as PL energies or decay times) is related to a distribution of QDs with different properties (ensemble average) or, alternatively, whether each QD explores these parameters in course of observation time (time average). To give more insight into this open question we have performed a series laser time-resolved experiments for single CdSe/ZnS QDs spin coated onto a quartz substrate at 293 K [4, 5]. It is well known that QDs show a strong photoluminescence (PL) intermittency (blinking) on time scales of ms to s [4–6]. We analysed blinking events by the change point analysis (CPA) [6] which allows detecting optical properties for each individual PL intensity of a single QD during a blinking time trace. As we have shown recently with an adequate time resolution [4] PL intensities vary continuously during a blinking time trace covering high, “dim” and low PL intensities. We also followed spectral diffusion (detected via energy jumps ΔE between 2 spectrally separated detection channels) of the PL of a single QD as a function of the intermittent PL intensity during a blinking time trace as is shown in Fig. 1 (top). Two observations immediately emerge. Firstly, the average PL energy at a given PL intensity (open circles) shifts (after an initial ≈ 10 meV “jump” to higher energies) by ΔE ≈ 30 meV to lower energy with decreasing PL intensity between the 2 given (blue) lines in Fig. 1. The line on the right marks the maximum Imax of the PL intensity distribution given in the bottom part of Fig. 1. The line on the left marks 0.1 Imax. This latter intensity corresponds to the limit at which we can for sensitivity reasons discriminate between different spectral components in an ensemble experiment. Secondly, for a given PL intensity we obtain as is shown in Fig. 1 (middle) a Gaussian distribution σ of spectral energies (spectral diffusion) of σ ≈ 20–30 meV at a selected PL intensity during a blinking time trace which is considerably broader than the experimental error but narrower than the