Modeling the crystal-field splitting of energy levels of Er3+ (4f11) in charge-compensated sites of KPb2Cl5 (original) (raw)
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Journal of Applied Physics, 2006
A point-charge lattice-sum model corrected for induced multipoles is used to investigate the crystal-field splitting of the 2S+1 L J energy levels of Er 3+ ͑4f 11 ͒ ions that occupy charge-compensated sites in the laser host crystal KPb 2 Cl 5 . Spectroscopic data are reported and analyzed for Er 3+ between 1550 and 440 nm at cryogenic temperatures. The crystal-field ͑Stark͒ splitting of the ground-state manifold 4 I 15/2 and the splitting of individual excited manifolds of Er 3+ are established from analyses of temperature-dependent ͑hot band͒ absorption spectra. The analyses confirm the Stark splitting of the 4 I J and 4 F 9/2 manifolds that are reported in the literature. From an analysis of the data, it appears that only one of the two possible Pb 2+ sites serving as a charge-compensated site for Er 3+ is involved in the optical activity of the Er 3+ ions. From an examination of the crystallographic data of KPb 2 Cl 5 , we identify a possible site for the optically active Er 3+ ion in the lattice and calculate the lattice-sum components for that site. These components are used to evaluate the crystal-field splitting of the energy levels of Er 3+ at that site. The charge-compensation model assumes that Er 3+ substitutes for Pb 2+ in the Pb͑2͒ site with a vacancy in a nearby K + site. To obtain the best overall agreement between calculated and experimental levels, the position of the Er 3+ ion is treated as an adjustable parameter along the quantization axis. Individual manifold centroids of the Er 3+ ion are also varied. From a least-squares fitting analysis, we obtain a rms deviation of 10 cm −1 between 48 calculated-to-observed Stark levels.
Energy level structure and excited-state absorption properties of Er^3+-doped KPb_2Cl_5
Journal of the Optical Society of America B, 2007
We present a detailed study of the spectroscopy and fluorescence properties of the Er: KPb 2 Cl 5 laser crystal, together with complementary data to complete the existing literature in the visible and near UV spectral domain. It deals with fluorescence decays, with anti-Stokes emission spectra and of calibration of excited-state absorption and emission spectra in the cross-section unit in the region of optical excitation around 800 nm. It brings new data for analyzing laser operation under one-and two-photon excitation conditions and for characterizing the involved energy transfer processes.
Growth and characterization of Er-doped KPb< sub> 2 Cl< sub> 5 as laser host crystal
2003
Single crystals of KPb2Cl5 were grown by vertical Bridgman technique from purified and synthesized material doped with Erbium up to a concentration of 5mol% ErCl3. The purification was performed by zone refining at a rate of 3cm/hr for 30 passes, with a final refining at a rate of 1mm/hr. Segregation coefficient of Er3+ ions was found to be∼ 0.5 for KPb2Cl5. The transmission through a 12-mm thick crystal was found to be∼ 80%, the mid-infrared and visible up-conversion luminescence spectra are reported.
DFT study and XPS measurements elucidating the electronic and optical properties of KPb2Cl5
Optical Materials, 2020
We report on a complex study employing both theoretical and experimental methods with the aim of detailed elucidating the electronic and optical properties of potassium lead chloride, KPb 2 Cl 5. In particular, we employ possibilities of X-ray photoelectron spectroscopy (XPS) to measure for an optical quality KPb 2 Cl 5 crystal the binding energies of the core-level electrons as well as to elucidate the peculiarity of the energy distribution of the valence electrons associated with the atoms composing the compound under study. The XPS data reveal low hygroscopicity of the KPb 2 Cl 5 crystal and minor transformation of the Pb 2+ ions to Pb 0 under treatment of the crystal surface with middle-energy Ar + bombardment. Furthermore, in the present work we apply different approaches for exchange-correlation potential to find how different factors affect the theoretical curve of total density of states in comparison with the valence-band XPS spectrum. The Tran-Blaha modified Becke-Johnson (TB-mBJ) potential, including spin-orbital effect and the Coulomb repulsion (Hubbard parameter U), is found to give the most reliable theoretical electronic structure of KPb 2 Cl 5. Based on these findings, detailed studies on the occupation of the valence and conduction bands by electronic states associated with the atoms composing the KPb 2 Cl 5 compound as well as on the optical properties are performed in the present work.
Ultraviolet spectra of KPb 2 Cl 5 : Er
Applied Physics Letters
The vacuum ultraviolet excitation and ultraviolet-visible emission spectra are reported for the laser and upconverter material KPb 2 Cl 5 :Er 3+ . The low-phonon energies of the host lattice enable, in addition to the ten luminescent states of Er 3+ in the visible and infrared spectral regions at room temperature, the observation of a further two luminescent multiplet terms in the ultraviolet spectral region at 10 K. A careful distinction is made between 4f 11 –4f 11 Er 3+ transitions and the band to band and Pb 2+ transitions. © 2008 American Institute of Physics. ͓DOI: 10.1063/1.2896297͔ Transparent crystals of erbium-doped KPb 2 Cl 5 of good optical quality are readily grown 1–3 and serve as an attractive material for upconversion, infrared lasing, and anti-Stokes laser cooling. 4 The chemical and mechanical stabilities of KPb 2 Cl 5 are superior to those of other rare earth chloride host lattices. As shown by Raman spectroscopy, the highest energy optical phonon of the KPb 2 Cl ...
New laser crystals based on KPb2Cl5 for IR region
Materials Science and Engineering: B, 2001
The KPb 2 Cl 5 single crystals, doped by different Rare Earth ions were grown. The RE segregation coefficient was found to decrease from 1.0 to 0.15 in the set from Nd to Yb. Spectroscopic properties and luminescence decay were studied, stimulated emission was demonstrated at 1.06 mm (Nd 3 + ) and at 2.43 mm (Dy 3 + ). : S 0 9 2 1 -5 1 0 7 ( 0 0 ) 0 0 7 3 5 -2
Le Journal de Physique Colloques, 1976
On a diffusément étudié la réorientation de dipôles ioniques dans leur état électronique fondamental tels que, par exemple, les dipôles lacune-impureté dans les halogénures alcalins. Récemment un phénomène de réorientation a été observé même à très basse température quand les dipôles L. I. ont absorbé de la lumière, c'est-à-dire, quand ils se trouvent dans l'état électronique excité (e. e. e.). L'effet est dû à l'abaissement de la barrière ionique d'énergie, induite par l'excitation du système électronique (modèle à diffusion). D'après ceci on a écrit des équations dans le but de discuter les procès de réorientation qui ont lieu dans l'e. e. e. du Pb ++ dans une structure ordonnée de dipôles L. I. (phase de Suzuki) dans KC1. L'efficacité de réorientation dans l'e. e. e. est thermiquement activée et sa distribution spectrale est étroitement liée au spectre d'absorption optique. On a étudié les vies moyennes radiatives entre 78-300 K dans KC1 : Pb soit quand Pb ++ est lié à un défaut simple soit quand il fait partie de la phase complexe de Suzuki. On a trouvé trois vies moyennes différentes : deux d'entre elles sont indépendantes de la température, tandis que la troisième croît, lorsque la température baisse. Enfin on a analysé les spectres d'excitation et d'émission de photoluminescence dans KC1 : Pb entre 20-300 K, en employant une très bonne résolution.
Analysis of spectra of neat and lanthanide ion-doped KPb2Cl5 excited by synchrotron radiation
physica status solidi (b), 2012
The excitation and emission spectra of neat K 2 PbCl 5 , and also doped with the lanthanide ions Pr 3þ , Nd 3þ , Er 3þ and Tm 3þ have been recorded at temperatures down to 10 K using synchrotron radiation. To facilitate the spectral assignments, a first principles calculation has been performed and despite its inaccuracies it confirms the nature of the lower energy levels of this system. The lowest energy transitions in the excitation spectrum are Pb 2þ -centred, whereas the band gap transitions, which are essentially of a charge transfer (CT) nature, are at shorter wavelengths. The emission transitions are likewise assigned to those from the Pb 2þ 3 P 1,0 states, and from the band gap. The Stokes shift of the latter transition is $18 000 cm À1 . Under synchrotron radiation excitation, the energy transfer from the host or Pb 2þ levels to 4f N lanthanide ion levels is not efficient.
2003 Conference on Lasers and Electro-Optics Europe (CLEO/Europe 2003) (IEEE Cat. No.03TH8666), 2003
ABSTRACT In this paper, optical spectra, luminescence decays and up-conversion processes in Er3+: KPb2Cl5 crystals, grown by Bridgman technique were studied. The luminescence spectra were recorded under UV and LD excitation, intensity parameters were determined by Judd-Ofelt method; radiative and radiationless transition probabilities were calculated. Luminescence kinetics from excited Er3+ levels, studied under its selective laser excitation, concentration quenching and up conversion processes, were considered. The conclusion is made that the Er3+:KPC crystals can be considered as one of the most promising active media for VIS and IR solid-state up-conversion LD pumped lasers with extremely low Stocks' losses.
Ultraviolet spectra of KPb[sub 2]Cl[sub 5]:Er[sup 3+]
Applied Physics Letters, 2008
The vacuum ultraviolet excitation and ultraviolet-visible emission spectra are reported for the laser and upconverter material KPb 2 Cl 5 :Er 3+ . The low-phonon energies of the host lattice enable, in addition to the ten luminescent states of Er 3+ in the visible and infrared spectral regions at room temperature, the observation of a further two luminescent multiplet terms in the ultraviolet spectral region at 10 K. A careful distinction is made between 4f 11 -4f 11 Er 3+ transitions and the band to band and Pb 2+ transitions.