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The shielding and spectroscopic properties of Pr + 3 and Pr3+/Ho3+-codoped tellurite glass were investigated. The intensity parameters (Ω2 = 3.24-, Ω4 = 1.64-, Ω6 = 1.10 × 10−20 cm2) as well as the radiative lifetimes of 3F4 + 5S2 and 5I6 excited states of Ho3+ ions were equal to 301 μs and 3.0 μs, respectively. The former value appears to be much higher than that obtained from the lifetime measurement, indicating the presence of various energy transfer processes. The NIR spectrum of Pr3+/Ho3+-co-doped tellurite glass is dominated by strong Ho3+: 5I6 emission at around 1200 nm, being the result of the energy transfer from Pr3+ to Ho3+ ions. The shielding effectiveness of the prepared glasses showed good performance against high-energy photons. These findings suggest that the prepared glasses could be used in laser technology such as photodynamic therapy (PDT) treatment procedures and as shielding for radiation protection. [ABSTRACT FROM AUTHOR]

To increase the emission intensity of Pr SP 3+ sp ions, Yb SP 3+ sp ions appear as an efficient sensitizer [[13]]. Due to a non-exponential character of the decay data, we have determined the experimental lifetime as being equal to the effective lifetime defined as HT ht Graph (4) Graph: Fig. [[36]]) HT ht Graph (5)where I i SB Pr-Yb sb and I i SB Pr sb are the effective lifetimes with and without Yb SP 3+ sp -coping, respectively, but for the same concentration of Pr SP 3+ sp ions. Emission spectra Emission spectra of Ln-doped samples TPr and TPrYb were measured in the same conditions allowing one to compare their relative intensities; additionally, in order to demonstrate the effect of the Pr SP 3+ sp ion concentration ( I N i SB Pr sb ; see Table 1) on the emission spectra, the PL signal of both samples (in arbitrary units) has been divided by I N i SB Pr sb . [Extracted from the article]

We have investigated the spectroscopic properties of Er3+-doped fluorotellurite glasses with the basic molar composition 75%TeO2-10%P2O5-10%ZnO-5%PbF2, modified by replacing 5% TeO2 by a metal oxide, namely WO3 or Nb2O5. The absorption edge of the glasses studied has been described within the Urbach approach, while the absorption and photoluminescence spectra have been analyzed in terms of the standard Judd-Ofelt theory, along with the photoluminescence decay of the 4I13/2 and 4S3/2 levels of the Er3+ ion. The absorption and emission spectra of the 4I15/2 ↔ 4I13/2 infrared transition have been analyzed within the McCumber theory to yield the peak emission cross-section and figure of merit for the amplifier gain. It appears that the fluorotellurite glass containing WO3 as a modifier is characterized by the largest figure of merit, indicating this matrix as a promising new host for doping with Er3+ ions. [ABSTRACT FROM AUTHOR]

A series of fluorotellurite glasses based on 70TeO2-5MxOy-10P²O5-10ZnO-5PbF2 in mol%, where MxOy = (WO3, Nb2O5) doped with 2400 ppm of Er2O3 have been prepared by the conventional melt quenching method. The influence of modifiers on thermal and optical properties of glasses has been analyzed. Thermal characteristics of glasses like the glass transition temperature Tg, the temperature for the crystallization onset Tx, the maximum crystallization temperature Tc, and the thermal stability parameter were determined by the DSC method. The ellipsometric data have provided Sellmeier-type dispersion relations of the refractive index of the investigated glasses. The optical parameters are used to calculate the molar refractivity, molar polarizability, oxide ion polarizability, molar cation polarizability, and a number of polarizable atoms per unit volume for every glass composition in order to interpret the refractive index of these glasses. [ABSTRACT FROM AUTHOR]

Abstract: The purpose of this work was to investigate the spectroscopic properties of Pr3+ ions of various concentrations embedded in a new matrix, namely a tellurite–tungstate glass with the molar composition 60%TeO2–27%WO3–10%PbO–3%La2O3 (TWPLa). The optical absorption edge of the TWPLa matrix has been described within the Urbach approach, while the absorption and fluorescence spectra of the Pr3+-doped TWPLa glasses have been analyzed in terms of the standard Judd–Ofelt (J–O) theory along with the luminescence decay of the 3P0 and 1D2 levels of the Pr3+ ion. A significant influence of the Pr3+ ion concentration on the photoluminescence intensity as well as on decrease of the lifetimes of both levels has been explained by a non-radiative energy transfer between the ions through different cross-relaxation channels. The spectroscopic studies have been completed with ellipsometric measurements providing the dispersion relation of the refractive index of the investigated glasses that has been taken into account in the J–O analysis. [Copyright &y& Elsevier]

The improved approach for analysis of the thin film optical spectra exhibiting the interference fringes is presented. It is shown that, based on the positions of adjacent extrema, the interference order numbers can be easily identified allowing for determination of a model-free normal dispersion of the refraction coefficient provided the film thickness is known from an independent measurement. The usefulness of the presented method is illustrated by the analysis of the reflection spectra obtained for thin films of 3, 4, 9, 10-perylene tetracarboxylic dianhydride (PTCDA) with various thicknesses determined with the atomic force microscopy (AFM). [ABSTRACT FROM AUTHOR]

The optical reflection measurements of polyvinylocarbazole (PVK) and polyazomethine (PPI) thin films have been done by means of optical profilometry (OP) exhibiting many advantages in surface and subsurface investigations. The obtained OP images clearly demonstrate that the thickness of the polymer films under investigation is not uniform over their lateral dimensions. For the PVK thin film, the fast Fourier transform (FFT) in the inverse space of the OP image is also presented along with distribution of the surface highs. [ABSTRACT FROM AUTHOR]

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Copyright of Polimery is the property of Industrial Chemistry Research Institute and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Transmission and fundamental reflectivity studies, completed on amorphous Zn-P thin films, allowed us to obtain parameters describing the fundamental absorption edge, i.e., the optical pseudogap EG, Urbach energy EU and exponential edge parameter ET. All these data, together with the results of earlier transport measurements, have been utilized in developing simple models of electronic structure (distribution of electronic states) for amorphous Zn-P thin films of two compositions, i.e., Zn57P43 (near stoichiometry of Zn3P2) and Zn32P68 (near stoichiometry of ZnP2). [ABSTRACT FROM AUTHOR]

The paper deals with investigation of the white Lambertian standards by means of optical methods, i.e., the bidirectional reflection distribution function (BRDF) method and the reflectance study with an integrating sphere. All measurements have been made using the L*a*b* color system. The effect of the choice of a standard on values of trichromatic parameters and the effect of aging of standards is discussed. [ABSTRACT FROM AUTHOR]

We have investigated the spectroscopic properties of Er3+-doped fluorotellurite glasses with the basic molar composition 75%TeO2-10%P2O5-10%ZnO-5%PbF2, modified by replacing 5% TeO2 by a metal oxide, namely WO3 or Nb2O5. The absorption edge of the glasses studied has been described within the Urbach approach, while the absorption and photoluminescence spectra have been analyzed in terms of the standard Judd-Ofelt theory, along with the photoluminescence decay of the 4I13/2 and 4S3/2 levels of the Er3+ ion. The absorption and emission spectra of the 4I15/2 ↔ 4I13/2 infrared transition have been analyzed within the McCumber theory to yield the peak emission cross-section and figure of merit for the amplifier gain. It appears that the fluorotellurite glass containing WO3 as a modifier is characterized by the largest figure of merit, indicating this matrix as a promising new host for doping with Er3+ ions. [ABSTRACT FROM AUTHOR]

Abstract: Multicomponent telluride-tungstate glasses containing Nd3+ and Er3+ ions were studied experimentally at 77 and 293K using spectroscopic methods. The Judd–Ofelt intensity parameters were derived from the absorption spectra and used to calculate the radiative lifetimes and branching ratios. The quantum efficiency η =0.95 of the 4F3/2 level of Nd3+ ion is higher than the typical value of other tellurite-based glasses. For low concentration of Er3+ ions, the luminescence decay of the 4S3/2 and 4I11/2 levels is governed by radiative transitions and multiphonon relaxation involving the Te-O highest energy vibrations. [Copyright &y& Elsevier]

Abstract: Optical transmission and fundamental reflectivity spectra of aromatic polyazomethine thin films, obtained by vacuum evaporation via the polycondensation process have been investigated in the wide spectral range 0.49–6.2eV. As initial monomers, terephaldehyde (TPA) and one of four different amines, i.e. paraphenylene-diamine (PPDA), 7,2-diamino-fluorene, 1,1′-biphenyl-3,3′,4,4′-tetramine and 3-amino-4-(1-naphthyldiazenyl)phenylamine (fat brown RR) have been used, respectively. Amorphous character of these films was confirmed by the results of X-ray diffraction and AFM investigations. Absorption coefficient of the films has been obtained and the edge of absorption seems to be similar to the absorption edge typical for amorphous semiconductors, what allowed to obtain the Urbach energy and E T parameter. The energy gaps of the films, following the Tauc relation, are found to change from 2.05 to 2.4eV, depending on the length of conjugated part of the polymer chain. Absorption bands above the absorption edge, observed for different polyazomethine films are connected with their chemical structure and possible electronic transitions. [Copyright &y& Elsevier]