共查询到20条相似文献,搜索用时 15 毫秒
1.
I. A. Demichev A. I. Ignat’ev N. V. Nikonorov E. M. Sgibnev A. I. Sidorov T. A. Khrushcheva T. A. Shakhverdov 《Optics and Spectroscopy》2014,116(4):587-592
The luminescence spectra of silicate glasses with silver introduced by ion exchange have been investigated. It is shown that silver introduced into glass by ion exchange exists not only in the form of ions, but also as neutral atoms and charged and neutral molecular clusters, which provide intense luminescence in the visible spectral range. Cerium ions in glass facilitate the formation of neutral molecular silver clusters, due to which the luminescence intensity increases. It is shown that Ag n -Ce x+ complexes can be formed in glass containing cerium ions and neutral molecular silver clusters. 相似文献
2.
E. V. Kolobkova N. V. Nikonorov A. I. Sidorov T. A. Shakhverdov 《Optics and Spectroscopy》2013,114(2):236-239
Luminescence spectra of silver-containing oxyfluoride glasses have been investigated in the excitation spectral range of 360–480 nm. Analysis of the luminescence spectra shows that silver in oxyfluoride glasses that contain no strong reducers and were subjected to heat treatment affecting redox processes exists in the form of neutral atoms and neutral molecular Ag2, Ag3, and Ag4 clusters. 相似文献
3.
K. V. Oreshkina V. D. Dubrovin A. I. Ignat’ev N. V. Nikonorov 《Optics and Spectroscopy》2017,123(4):590-596
The effect of silver on the optical, spectral-luminescent, and crystallization properties of bromide photo-thermo-refractive glasses is studied. Multicomponent photosensitive glasses of the Na2O–ZnO–Al2O3–SiO2 system with photosensitizing agents (cerium, antimony, silver) and halogenides (fluorine and bromine) are synthesized. Ultraviolet irradiation and thermal treatment below the glass-transition temperature of the glasses cause the formation of silver molecular clusters, which exhibit luminescence in the visible and infrared regions. UV irradiation and thermal treatment of glasses above the glass-transition temperature lead to the growth of silver nanoparticles with plasmon resonance peak in the region of 420 nm. Further thermal treatment of glasses above the glass-transition temperature shifts the plasmon-resonance maximum by 70 nm to longer wavelengths, which is related to the growth of a crystalline shell consisting of mixed silver and sodium bromides on nanoparticles. This formation of a crystalline phase on colloidal centers results in a local increase in the refractive index of the irradiated region by +Δn ~ 900 ppm compared to the nonirradiated region. Photo-thermo-refractive glasses with increased silver concentration are promising photosensitive materials for creating holographic optical elements and devices for line narrowing and stabilizing filters, spectral beam combiners, and filters for increasing the spectral brightness of laser diodes. A positive change in the refractive index of Photo-thermo-refractive glasses provides the possibility of recording in them 3D waveguide and integrated-optical structures. 相似文献
4.
Changes in the absorption and luminescence spectra of fluorophosphate glasses doped with PbSe caused by low-temperature Ag+–Na+ ion exchange are considered. It is found that the silver distribution gradient in a near-surface layer about 16 μm thick leads to two different processes of interaction between metal and semiconductor nanoparticles. PbSe molecular clusters and quantum dots more efficiently grow in deep layers with a low silver concentration. The near-surface glass layers with a high silver concentration exhibit formation of Ag metal nanoparticles, on the surface of which interaction with PbSe molecular clusters leads to the formation of Ag–Se–Pb bonds, which transform into Ag2Se layers in the process of heat treatment. The appearance of the new phase is confirmed by X-ray diffraction. 相似文献
5.
It is shown experimentally that a rise in the sodium halogenide (NaCl, NaBr) concentration in photothermorefractive glasses increases the intensity of luminescence from silver neutral molecular clusters. Substitution of NaBr for NaCl with their concentration being the same shifts the luminescence band toward longer waves and raises its intensity. These findings can be explained by the formation of molecular clusters of type Ag n -Hal (Hal = Cl, Br) in photothermorefractive glass. 相似文献
6.
G. E. Malashkevich A. V. Semchenko A. A. Sukhodola A. P. Stupak A. V. Sukhodolov B. V. Plyushch V. V. Sidskiĭ G. A. Denisenko 《Physics of the Solid State》2008,50(8):1464-1472
The introduction of silver into the samarium-containing silica glasses prepared by the original solgel method leads to the formation of complex optical centers involving samarium ions and simple and/or complex silver ions. These centers are characterized by the effective sensitization of Sm3+ luminescence by Ag+, (Ag2)+, and (Ag+)2 ions according to the exchange mechanism for, at least, Sm3+-Ag+ centers. The formation of Sm-Ag centers is accompanied by an increase in the concentration of nonbridging oxygen ions, which prevent the reduction of silver ions by hydrogen. Silver nanoparticles formed in small amounts upon this reduction are effective quenchers of luminescence from the corresponding excited states of Sm3+ ions. 相似文献
7.
Zh. O. Lipatova E. V. Kolobkova A. I. Sidorov N. V. Nikonorov 《Optics and Spectroscopy》2016,121(2):200-209
The influence of sodium nanoparticles and secondary heat treatment conditions on the spectralluminescent characteristics of fluorophosphate glasses with PbSe molecular clusters and quantum dots is studied. Experiments with glasses containing no sodium nanoparticles show that their thermal treatment leads to the formation of molecular clusters with subsequent formation of quantum dots having an intense luminescence. The results of numerical simulation for glasses with sodium nanoparticles shows that heat treatment leads to formation of a sodium fluoride shell on the nanoparticles surface. It is shown that quenching of the luminescence of PbSe molecular clusters and quantum dots takes place in these glasses. 相似文献
8.
N. V. Nikonorov A. I. Sidorov V. A. Tsekhomskii T. A. Shakhverdov 《Optics and Spectroscopy》2013,114(3):379-383
Broadband luminescence in the visible spectral range has been investigated for copper-containing potassium-aluminum borate glasses. It is shown that the luminescence in initial glasses (before their heat treatment) is due to the presence of molecular clusters Cu n (n < 10) in them. Chemical reactions during heat treatment lead to the formation of Cu n Cl x and Cu n O x clusters with luminescence bands lying in the spectral range of 450–600 nm. 相似文献
9.
Rare-earth doped YF3 nanocrystals embedded in sol–gel silica glass matrix for white light generation
J. Méndez-Ramos A. Santana-Alonso A.C. Yanes J. del-Castillo V.D. Rodríguez 《Journal of luminescence》2010,130(12):2508-2511
YF3 nanocrystals triply-doped with Yb3+, Ho3+ and Tm3+ ions embedded in amorphous silica matrix have been successfully obtained by heat treatment of precursor sol–gel glasses for the first time to our knowledge and confirmed by X-ray diffraction and luminescence measurements. Simultaneous UV and visible efficient up-conversion emissions, with well-resolved Stark structure, under 980 nm infrared pump are observed, indicating the effective partition of rare-earth ions into a crystalline-like environment of the YF3 nanocrystals. Corresponding energy transfer mechanisms have been analyzed and overall colour emission has been quantified in terms of standard chromaticity diagram. By an adequate doping level and heat treatment temperature of precursor sol–gel glasses, a bright white colour has been accomplished, close to the standard equal energy white light illumination point, with potential applications in photo-electronic devices and information processing. 相似文献
10.
Metastable fragmentation of silver bromide clusters 总被引:2,自引:0,他引:2
J.-M. L'Hermite F. Rabilloud L. Marcou P. Labastie 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,14(3):323-330
The abundance spectra and the fragmentation channels of silver bromide clusters have been measured and analyzed. The most
abundant species are AgnBrn - 1
+ and AgnBrn + 1
- and Ag14Br13
+ is a magic number, revealing their ionic nature. However, some features depart from what is generally observed for alkali-halide
ionic clusters. From a certain size, AgnBrn - 1
+ is no more the main series, and AgnBr n - 2, 3
+ series become almost as important. The fast fragmentation induced by a UV laser makes the cations lose more bromine than
silver ions and lead to more silver-rich clusters. Negative ions mass spectra contain also species with more silver atoms
than required by stoichiometry. We have investigated the metastable fragmentation of the cations using a new experimental
method. The large majority of the cations release mainly a neutral Ag3Br3 cluster. These decay channels are in full agreement with our recent ab initio DFT calculations, which show that Ag+-Ag+ repulsion is reduced due to a globally attractive interaction of their d orbitals. This effect leads to a particularly stable trimer (AgBr)3 and to quasi-planar cyclic structures of (AgBr)n clusters up to n = 6. We have shown that these two features may be extended to other silver halides, to silver hydroxides (AgOH)n, and to cuprous halide compounds.
Received 9 November 2000 and Received in final form 25 January 2001 相似文献
11.
The structural, energy, and optical properties of charged and neutral molecular clusters (MCs) of silver Agn (n = 2–5) have been simulated within the density functional theory (DFT). It has been shown that the electronic absorption spectrum of neutral MCs is shifted toward lower energies compared to the charged ones. The strengths of the oscillators of neutral MCs are mainly larger than the ones of charged MCs. A comparison of the simulation results with the previously obtained experimental ones for glasses with silver MCs has been carried out. 相似文献
12.
The possibility of double spectral conversion of UV radiation from the spectral range of 240–280 nm to the visible spectral region using luminescent glasses and fibers with antimony ions and molecular silver clusters is shown. Planar and fiber prototypes of UV radiation dosimeters are tested. It is shown that the sensitivities of dosimeter of the first and second types are 1400 and 360 mV/W/m2, respectively. 相似文献
13.
G. E. Malashkevich G. P. Shevchenko S. V. Serezhkina P. P. Pershukevich G. I. Semkova G. K. Glushonok 《Physics of the Solid State》2007,49(10):1891-1902
A sol-gel method is used to prepare GeO2-Eu2O3-Ag films in which the luminescence efficiency of Eu3+ ions during UV excitation is comparable to that in films activated by organic europium complexes. The luminescence spectra of these films are recorded, and the films are also studied using EPR and x-ray diffraction. The main origin of this effect is found to be complex Eu-Ag centers with a high quantum yield of the intracenter transfer of excitations to the rare-earth activator from silver ions and Ag m n+ oligomer clusters located on the surface of silver nanoparticles. 相似文献
14.
A. N. Babkina N. V. Nikonorov A. I. Sidorov P. S. Shirshnev T. A. Shakhverdov 《Optics and Spectroscopy》2014,116(1):84-90
Luminescence and luminescence-excitation spectra of potassium-aluminum borate glasses containing copper(I) and silver ions have been investigated in the temperature range of 20–300°C. It is shown that the luminescence thermochromic effect, which manifests itself in a blue spectral shift of the luminescence bands with an increase in temperature, occurs in glasses of all types, reaching a value of 100 nm. Heating leads to a red shift of luminescence-excitation bands by 20 nm and their broadening. Luminescence quenching occurs in glasses exhibiting photochromic effect at room temperature. An increase in temperature leads to weakening and, finally, disappearance of the photochromic effect in these glasses with subsequent occurrence of the luminescence thermochromic effect. 相似文献
15.
O. V. Ovchinnikov D. A. Minakov M. S. Smirnov P. V. Novikov A. N. Latyshev 《Journal of Applied Spectroscopy》2007,74(4):605-607
We use the photostimulated luminescence flash method to measure photoionization spectra of Ag2 clusters adsorbed on the surface of a ZnS single crystal. Adsorbed dimers of silver are prepared by treatment of the surface
of a ZnS single crystal in high vacuum with a beam of molecular Ag
2
+
ions followed by their neutralization. We show that the adsorbed dimers create two types of electron traps at energy levels
1.63 and 1.82 eV below the bottom of the conduction band.
__________
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 74, No. 4, pp. 545–547, July–August, 2007. 相似文献
16.
Optics and Spectroscopy - The formation of silver molecular clusters and nanoparticles in photo-thermo-refractive (PTR) glasses with different antimony contents has been investigated using ion... 相似文献
17.
UV–visible, infrared and Raman spectra, together with thermal properties, were measured for glasses from the system Bi2O3–B2O3–V2O5 before and after successive gamma irradiations. The UV–visible spectrum of the undoped glass before irradiation reveals five UV bands at 210, 275, 310, 350 nm, an intense band at 380 nm and a visible band at 420 nm due to the possible combined presence of trace iron impurities and Bi3+ ions. The V-doped glasses reveal six UV bands and two visible bands, probably arising from vanadium ions in three possible valencies, V3+, V4+ and V5+, beside that due to trace iron impurity beside Bi3+ ions. The spectra reveal an obvious resistance of the glasses to successive gamma irradiation. The Raman and infrared spectra show characteristic absorption bands, which indicate the sharing of Bi3+ ions as glass-forming (BiO6) octahedral units together with the presence of various groups of the borate network. 相似文献
18.
Europium-doped aluminophosphate glasses prepared by the melt-quenching technique have been studied by photoluminescence (PL) and X-ray photoelectron spectroscopy (XPS). The effects of silver and tin doping, and of further thermal processing on Eu3+ ions luminescence have been assessed. For the glass system containing only europium, Eu3+ PL observed under UV excitation is suggested to occur through energy transfer from the excited glass host. After silver and tin doping, an enhanced UV excited Eu3+ PL has been indicated to occur essentially due to radiative energy transfer from isolated Ag+ ions and/or two fold-coordinated Sn centers. Since thermal processing of the material leads to a quenching effect on Eu3+ PL and Ag nanoparticles (NPs) formation due to reduction of silver ions by tin, XPS was employed in order to investigate the possibility for Eu3+→Eu2+ reduction during HT as a potential source of the PL decrease. The data points towards Ag NPs as main responsible for the observed weakening of Eu3+ PL. 相似文献
19.
Undoped and TiO2-doped lead phosphate glasses were prepared. Ultraviolet (UV)–visible and Fourier transform-infrared (IR) absorption spectra of the prepared samples were measured before and after being subjected to doses of 30 and 60 kGy of gamma irradiation. The parent undoped lead phosphate glass reveals charge transfer UV absorption bands which are attributed to the presence of unavoidable iron impurities contaminated within the raw materials used for the preparation of the glasses and the sharing of divalent lead (Pb2+) ions. Experimental spectral data indicate that the doped titanium ions are involved in such glasses in two valences, namely the trivalent and tetravalent states. The predominant trivalent titanium (Ti3+) ions are characterized by its purple color and exhibiting two visible absorption bands at about 500–550 and 700–720 nm. The lesser tetravalent titanium (Ti4+) ions belong to the d0 configuration and generally exhibit only an UV absorption band. Spectral data show that gamma irradiation causes noticeable changes in the undoped and TiO2-doped samples in the UV range while the effects are limited in the visible range. The observed changes in the UV region are attributed to photochemical reactions while TiO2-doped samples show retardation or shielding toward continuous gamma irradiation together with the sharing of heavy Pb2+ ions. IR absorption spectra reveal the vibrations of several phosphate groups including the metaphosphate chains as the main structural building units together with the possible Pb?O vibrations. 相似文献
20.
Glasses containing silver, tin and europium were prepared by the melt-quenching technique with silver nanoparticles (NPs) being embedded upon heat treatment (HT). An intensification of Eu3+ ions emission was observed for non-resonant excitation around 270 nm, corresponding to UV absorption in the material. Optical measurements suggest that light absorption occurs at single Ag+ ions and/or twofold-coordinated Sn centers followed by energy transfer to europium which results in populating the 5D0 emitting state in Eu3+. After HT at 843 K, a quenching effect is observed on Eu3+ luminescence with increasing holding time in the 350–550 nm excitation range. The quenching effect shows with the presence of Ag NPs which may provide multipole radiationless pathways for excitation energy loss in europium ions. 相似文献