Phase conversion and spectral properties of long lasting phosphor Zn-3 (PO4)(2): Mn2+, Ga3+

A red long lasting phosphor Zn-3(PO4)(2): Mn2+ Ga3+ (ZPMG) was prepared by ceramic method, and phase conversion and spectral properties were investigated. Results indicated that the phase conversion from alpha-Zn-3(PO4), beta-Zn-3(PO4)(2) to gamma-Zn-3(PO4)(2) occurs with different manganese concentration incorporated and sinter process. The structural change induced by the phase transformation results in a remarkable difference in the spectral properties. The possible luminescence mechanism for this red LLP with different forms has been illustrated.

Synthesis and spectral properties of lutetium-doped CeF3 nanoparticles

CeF3 and lutetium-doped CeF3 nanoparticles with the dopant concentration of 17, 25, 30, 42 and 50 mol% (molar ratio, Lu/Ce) were synthesized. XRD patterns were indexed to a pure CeF3 hexagonal phase even under the dopant concentration of 50 mol%. Environmental scanning electron microscopy-field emission gun (ESEM-FEG) was used to characterize the morphology of the final products. From the luminescence spectra of the products, we can get a broad emission ranging from 290 to 400 nm with peak at 325 nm. Lutetium-doping increases the luminescence intensity. We got. the most intense luminescence at the dopant concentration of 30 mol%.

Spectral properties of rare-earth ions in nanocrystalline YAG : Re (Re = Ce3+, Pr3+, Tb3+)

Bulk and nanoscale powders of YAG:Re (Re = Ce, Pr, Tb) were synthesized by solid-state and sol-gel method. The changes of spectra and energy level were studied. Compared with the bulk YAG:Re (Re = Ce, Pr, Tb) crystals, the lattice parameter of YAG:Re (Re = Ce, Pr, Tb) nanocrystals decreases. It is also found that the excitation peaks of 5d energy levels shift in nanocrystals. The physical reason for spectral and energy level changes is a comprehensive result from the shift of energy centroid of the 5d orbit, the Coulomb interaction between 4f and 5d electrons and the crystal field splitting of the 5d energy level.

Hydrothermal synthesis and spectral properties of the Eu doped KZnF3

The polycrystals of KZnF3 : Eu have been synthesized by hydrothermal method at 220 degreesC, The product was characterized by XRD, XPS and SEM. The emission and excitation spectra of europium ion were measured. The existence of Eu2+ ion was confirmed by ESR and spectroscopy. The sites were possibly occupied by Eu2+ ions, charge compensation in this crystal were also discussed.

The spectral properties of BaB8O13:Eu,Tb phosphors

The luminescence properties of BaB8O13:xEu,yTb phosphors which were synthesized in air atmosphere have been studied. The emissions of europium(III), terbium(III) and europium(II) have been observed in BaB8O13:xEu, yTb phosphors. Electron paramagnetic resonance (EPR) studies were carried out. The intensities of EPR peaks of europium(II) are increased if terbium(III) is increased in BaB8O13:Eu3+,yTb(3+) phosphors. So the valence state of europium is influenced by terbium(III). These phenomena can be explained by an electron transfer mechanism. We found a new kind of method to prepare trichromatic phosphor that two rare earth ions activated in a BaB8O13 matrix.

THE VALENCE CHANGE FROM RE3+ TO RE2+ (RE-EQUIVALENT-TO-EU, SM, YB) IN SRB4O7-RE PREPARED IN AIR AND THE SPECTRAL PROPERTIES OF RE2+

A valence change from RE3+ to RE2+ (RE=Eu, Sm, Yb) was observed in samples of SrB4O7: RE prepared by solid state reaction at high temperature in air. The phosphors SrB4O7: RE2+ show efficient luminescence at room temperature. The broad band d-f emissions of Eu2+ and Yb2+ are at 367 and 360 nm respectively. The sharp line f-f emissions of the Sm2+ ion (5D0-F-7(J)) are in the range 680-780 nm. The probable reasons for the valence change of Eu, Sm and Yb in this host are discussed.

A review of spectral properties of plants and their potential use for crop/weed discrimination in row-crops

R. Zwiggelaar, 'A review of spectral properties of plants and their potential use for crop/weed discrimination in row-crops', Crop Protection 17 (3), 189-206 (1998)

Transition Metal Complexes with Ring Incorporated Thiosemicarbazones: Syntheses,Structures and Spectral Properties

In the present work,the chelating behaviour of thiosemicarbazones of a heterocyclic diketone, 2,6-diacetylpyridine is studied,with the aim of investigating the influence coordination exerts on their conformation and /or configuration, in connection with the nature of the metal and of the counter ion.The various possibilities like unsubstitution,ring incorporation at terminal nitrogen and condensation of one of the ketone group alone have been tried for ligand selection.Mainly first row transition metals like manganese,iron,nickel,copper,zinc and cadmium are studied.Metals like cobalt also were studied but could not result in fruitful isolation of the compound due to solubility problems.Different spectroscopic and characterization techniques have been utilized to reveal the nature of the metal and the ligands in coordinated metal complex.

Spectral properties, iron oxide content and provenance of Namib dune sands

This paper applies multispectral remote sensing techniques to map the Fe-oxide content over the entire Namib sand sea. Spectrometric analysis is applied to field samples to identify the reflectance properties of the dune sands which enable remotely sensed Fe-oxide mapping. The results indicate that the pattern of dune colour in the Namib sand sea arises from the mixing of at least two distinct sources of sand; a red component of high Fe-oxide content (present as a coating on the sand grains) which derives from the inland regions, particularly from major embayments into the Southern African escarpment; and a yellow coastal component of low Fe-oxide content which is brought into the area by northward-moving aeolian transport processes. These major provenances are separated by a mixing zone between 20 kin and 90 kin from the coast throughout the entire length of the sand sea. Previous workers have also recognised a third, fluvial, provenance, but the methodology applied here is not able to map this source as a distinct spectral component. (c) 2006 Elsevier B.V. All rights reserved.

Spectral properties, iron oxide content and provenance of Namib dune sands

This paper applies multispectral remote sensing techniques to map the Fe-oxide content over the entire Namib sand sea. Spectrometric analysis is applied to field samples to identify the reflectance properties of the dune sands which enable remotely sensed Fe-oxide mapping. The results indicate that the pattern of dune colour in the Namib sand sea arises from the mixing of at least two distinct sources of sand; a red component of high Fe-oxide content (present as a coating on the sand grains) which derives from the inland regions, particularly from major embayments into the Southern African escarpment; and a yellow coastal component of low Fe-oxide content which is brought into the area by northward-moving aeolian transport processes. These major provenances are separated by a mixing zone between 20 kin and 90 kin from the coast throughout the entire length of the sand sea. Previous workers have also recognised a third, fluvial, provenance, but the methodology applied here is not able to map this source as a distinct spectral component. (c) 2006 Elsevier B.V. All rights reserved.

Palladium and platinum complexes of 2-(2 '-carboxyphenylazo)-4-methylphenol: synthesis, structure and spectral properties

Reaction of 2-(2'-carboxyphenylazo)-4-methylphenol (H2L) with [M(PPh3)(2)Cl-2] (M = Pd, Pt) affords mixed-ligand complexes of type [M(PPh3)(L)]. Structures of both the complexes have been determined by X-ray crystallography. Both the complexes are square planar, where the 2-(2'-carboxyphenylazo)-4-methylphenol is coordinated to the metal center, via dissociation of the two acidic protons, as a dianionic tridentate O,N,O-donor, and the fourth position is occupied by the triphenylphosphine. These complexes show intense MLCT transitions in the visible region.

The temperature-dependent spectral properties of filter substrate materials in the far-infrared (6-40 mu m)

This paper presents the experimental results on the low temperature absorption and dispersion properties for a variety of frequently used infrared filter substrate materials. Index of refraction (n) and transmission spectra are presented for a range of temperatures 300-50 K for the Group IV materials silicon (Si) and germanium (Ge), and Group II-VI materials zinc selenide (ZnSe), zinc sulphide (ZnS) and cadmium telluride (CdTe). (C) 2003 Elsevier B.V. All rights reserved.

Solvability and spectral properties of integral equations on the real line: I. Weighted spaces of continuous functions

We consider in this paper the solvability of linear integral equations on the real line, in operator form (λ−K)φ=ψ, where and K is an integral operator. We impose conditions on the kernel, k, of K which ensure that K is bounded as an operator on . Let Xa denote the weighted space as |s|→∞}. Our first result is that if, additionally, |k(s,t)|⩽κ(s−t), with and κ(s)=O(|s|−b) as |s|→∞, for some b>1, then the spectrum of K is the same on Xa as on X, for 01. As an example where kernels of this latter form occur we discuss a boundary integral equation formulation of an impedance boundary value problem for the Helmholtz equation in a half-plane.