Site selective spectroscopy of rare earth doped ThO2

The individual sites present in ThO₂ doped with Eu³⁺ and Er³⁺ have been studied by site selective spectroscopy. A cubic site corresponding to a rare earth charge compensated distantly and two sites having local charge compensation have been identified. One of the locally compensated sites is present only at moderate temperature while the other is formed at higher temperatures and is stable to high temperatures. The measurements are related to catalytically excited fluorescence of ThO₂, previous luminescence measurements, and magnetic resonance experiments that observe the presence of local F^_ charge compensation of rare earth dopants.     

Radio-frequency spectrum analyzers based on rare earth ion doped crystals

We review recent demonstrations of wide band radio frequency (rf) spectral analyzers based on spectral hole burning technology. The optically carried rf signal can be analyzed with sub-MHz resolution over tens of GHz instantaneous bandwidth. PACS 42.50.Md; 76.30.Kg; 42.79.Hp; 95.55.Fm; 95.55.Jz     

14th International Feofilov Symposium on spectroscopy of crystals doped with rare earth and transition metal ions

Condensed-Matter Spectroscopy

14th International Feofilov Symposium on spectroscopy of crystals doped with rare earth and transition metal ions     

Infrared-to-visible and infrared-to-violet upconversion fluorescence of rare earth doped LaF3 nanocrystals

This paper reports that hexagonal-phase LaF3：Yb0.20^3＋,Er0.02^3＋ and LaF3：Yb0.20^3＋, Tm0.02^3＋ nanocrystals （NCs） were synthesized via a hydrothermal method. The transmission electron microscopy, selected area electron diffraction, powder x-ray diffraction, and thermogravimetric analysis are used to characterize the NCs. Under 980 nm excitation, the Yb^3＋/Er^3＋ and Yb^3＋/Tm^3＋ codoped NCs colloidal solutions present bright green and blue upconversion fluorescence, respectively. These NCs show efficient infrared-to-violet and infrared-to-visible upconversion. The upconversion fluo- rescence mechanisms of LaF2：Yb0.20^3＋, Er0.02^3＋ and LaF3：Yb0.20^3＋,Tm0.02^3＋ NCs are investigated with a 980-nm diode laser as excitation source.     

Spectrum broadening in phase-modulated coherent optical illumination

A method is proposed for broadening the spectrum available from a “phase-modulator”, thereby effecting an improvement in two-dimensional image quality when using coherent light.     

Photodichroic crystals for coherent optical data processing

The use of photodichroic alkali halide crystals as re-usable input, storage, and filter plane elements in a coherent optical computer are reviewed. Various recording methods and applications are presented with emphasis on the use of the M and M_A centres in NaF at room temperature.     

Phase changes in cubic rare earth crystals

An explanation is offered of the structural transitions and magnetic orderings in the cubic rare earth compounds LnX with particular emphasis on the anomalous spin arrangements observed in HoP, DyP and DyAs and in ErSb and ErP.     

Relation between optical breakdown field and stokes spectral broadening

The process which limits the diameter of self focal spots must also limit the Stokes self phase modulated spectral width. A simple analysis is consistent with data for nsec pulses in organic liquids.     

High resolution atomic coherent control via spectral phase manipulation of an optical frequency comb

We demonstrate high resolution coherent control of cold atomic rubidium utilizing spectral phase manipulation of a femtosecond optical frequency comb. Transient coherent accumulation is directly manifested by the enhancement of signal amplitude and spectral resolution via the pulse number. The combination of frequency comb technology and spectral phase manipulation enables coherent control techniques to enter a new regime with natural linewidth resolution.     

Conduction electron polarization in ferromagnetic rare earth crystals

We show that the average spin per atom in ferromagnetic rare earth metals is enhanced by means of a net spin polarisation of conduction electrons, arising as a consequence of multiple scattering of the conduction electrons.     

Diffuse phase transition in rare earth ion doped SBN

The diffuse transition of a rare earth ion doped SBN (Ba_xSr_1?xNb₂O₆) was studied by measuring the spontaneous polarization P_s, and the dielectric constant ?. The phase transition of SBN can be regarded as a special case of a second order transition.     

Electrical relaxation in rare earth doped cubic lead fluoride

Audio frequency complex impedance measurements are performed over the temperature range 5.5-380 K on lead fluoride doped with ten rare earths and lanthanum at various concentrations. It is found that the complexity of the relaxation spectrum increases as the size of the trivalent ion decreases. Specifically, for the largest rare earths, only one relaxation is found. That relaxation is different from the cases in the alkaline earth fluorides where only one relaxation is observed in that the reorientation enthalpy depends strongly upon ion size. Double-doped samples are studied to determine whether the relaxation is due to a simple site or a cluster. For the smallest rare earths, however, at least nine relaxations are found. The concentration studies indicate multiple relaxations for certain sites. Both simple sites and clusters are observed for small rare earths.     

Zero point shift in rare earth doped CaF2

The line position of the 4f ⁷(⁸ S _7/2)→4f ⁶5d (4130 Å) transition in Eu:CaF₂ has been measured as well as its shift under the action of uniaxial stress. These data are used to estimate the isotope shift due to the zero point vibrations. There is reasonable agreement with that measured directly in Sm:CaF₂.     

High field electrical properties of CdF2 crystals doped with rare earth ions

The electrical properties of CdF₂ crystals doped with Eu³⁺ and Gd³⁺ are described. A reversible “forming” effect is observed under high electric fields. The effect seems to be connected with a reversible modification of the potential barrier at the metal-insulator contact.     

The optical properties of trivalent rare earth ions (Er3+) doped borotellurite glass

Erbium doped borotellurite glass has been fabricated by using conventional melting method. The density and molar volume have been calculated and analyzed while their optical properties were studied by measuring the optical absorption and luminescence spectra at room temperature. From the XRD results, since the patterns do not exhibit any diffraction line thus it confirms their amorphous nature. It is found that the density of the glass samples increased and the molar volume decreased with respect to Er ions content. Meanwhile, the upconversion emissions centered at 487, 523, 558, 642, 695 and 782 nm have been observed under the 650 nm excitation in the ⁴ F _9/2 level. Some other results will be analysed and discussed in details.     

Satellite lines in the optical spectrum of Mn2+ in rare earth double nitrate crystals

Satellite lines have been observed in the spectra of Mn²⁺ in crystals of lanthanum manganese double nitrate and praseodymium manganese double nitrate doped with impurity ions on Mn²⁺ sites and rare-earth sites. The lattice sites in the neighbourhood of the Mn²⁺ ions which must be occupied by impurity ions to produce satellite lines have been identified. Besides the satellite lines a common line shift was observed, which was concentration dependent.Project of the Sonderforschungsbereich Festkörperspektroskopie Darmstadt-Frankfurt supported by the Deutsche Forschungsgemeinschaft.     

Growth aspects,spectral, thermal and hardness studies of rare earth cerium(III)nitrate doped zinc(tris) thiourea sulphate single crystals

Single crystals of pure and cerium(III)nitrate doped zinc(tris) thiourea sulphate (ZTS) were grown from aqueous solution by slow evaporation method. The cell parameters of the grown crystals were determined by single crystal X-ray diffraction analysis. Powder X-ray diffraction patterns were recorded and indexed for the structural confirmation. The presence of functional group in the compound has been confirmed by FTIR analysis. UV–vis absorption spectrum has been recorded to determine the cut-off wavelength of the crystal. TGA/DTA studies show thermal stability of the grown crystals. SEM-EDX analysis revealed the incorporation of the impurity (Ce³⁺) into ZTS crystals. The microhardness study reveals that the hardness number (H_v) increases with load for all the grown crystals of this work. From the values of work hardening coefficients, it was concluded that pure and cerium nitrate doped ZTS crystals belong to the category of soft materials. The second harmonic generation of cerium(III)nitrate doped ZTS crystals was confirmed by Kurtz–Perry powder method using Nd:YAG laser.     

Magnetic and quadrupole interactions of rare earth in bone crystals

From emission Mössbauer spectra performed on¹⁶¹Tb-bone samples, the Mössbauer and hyperfine parameters are obtained. The lattice components of the EFG acting at Dy in bone crystals are evaluated. These values show that the rare earth ions are fixed on hydroxyapatite crystallites in a hydroxyde environment.