Safe and Scalable Polyethylene Glycol-Assisted Hydrothermal Synthesis and Laser Cooling of 10%Yb3+:LiLuF4 Crystals

Rare earth doped lithium fluorides are a class of materials with a wide variety of optical applications, but the hazardous reagents used in their synthesis often restrict the amount of product that can be created at one time. In this work, 10%Yb3+:LiLuF4 (Yb:LLF) crystals have been synthesized through a safe and scalable polyethylene glycol (PEG)-assisted hydrothermal method. A combination of X-ray diffraction (XRD) analysis, scanning electron microscopy (SEM), and photoluminescence (PL) measurements were used to characterize the obtained materials. The influence of reaction temperature, time, fluoride source, and precursor amount on the shape and size of the Yb:LLF crystals are also discussed. Calibrated PL spectra of Yb3+ ions show laser cooling to more than 15 K below room temperature in air and 5 K in deionized water under 1020 nm diode laser excitation measured at a laser power of 50 mW

Selective laser spectroscopy of the bixbyite-type yttrium scandate doped by rare-earth ions

Yttrium scandate crystals doped by Nd3+ and Tm3+ ions have been obtained in the form of a fiber through the laser-heated pedestal growth (LHPG) method. Three types of optical centers of Nd3+ and Tm3+ have been recorded by the selective laser spectroscopy methods. Two dominant centers form due to substitution of the rare-earth ions for Y3+ and Sc3+ in the structural site of C2. In the case of Nd3+:YScO3, the third one is aggregate pair center Nd3+ - Nd3+ which forms due to substitution of basic ions (Y3+ or Sc3+) in neighboring MO6 polyhedra shared the edge. In the case of Tm3+:YScO3, the third optical center form due to substitution of Tm3+ for Y3+ or Sc3+ in the octahedra MO6 with symmetry site of C3i. The lifetime have been estimated for Nd3+ and Tm3+ ions occupied MO6 polyhedra with symmetry sites of C2 and C3i in the YScO3 crystal fibers. Stark level schematic of 2F3/2, 4I11/2, and 4I9/2 multiplets of Nd3+ ions have been built for both centers of C2 in the YScO3 crystal fibe

Safe and Scalable Polyethylene Glycol-Assisted Hydrothermal Synthesis and Laser Cooling of 10%Yb³⁺:LiLuF₄ Crystals

Rare earth doped lithium fluorides are a class of materials with a wide variety of optical applications, but the hazardous reagents used in their synthesis often restrict the amount of product that can be created at one time. In this work, 10%Yb3+:LiLuF4 (Yb:LLF) crystals have been synthesized through a safe and scalable polyethylene glycol (PEG)-assisted hydrothermal method. A combination of X-ray diffraction (XRD) analysis, scanning electron microscopy (SEM), and photoluminescence (PL) measurements were used to characterize the obtained materials. The influence of reaction temperature, time, fluoride source, and precursor amount on the shape and size of the Yb:LLF crystals are also discussed. Calibrated PL spectra of Yb3+ ions show laser cooling to more than 15 K below room temperature in air and 5 K in deionized water under 1020 nm diode laser excitation measured at a laser power of 50 mW

Solid-State Laser Refrigeration at GPa Pressures

Although solid-state laser-refrigeration recently has been demonstrated to reach cryogenic temperatures in vacuum, to date the solid-state laser refrigeration of materials at elevated pressure conditions has remained unexplored. Here we demonstrate the laser cooling of ytterbium-doped yttirum-lithium-fluoride (10%Yb3+:YLiF4, or Yb:YLF)>17K below room temperature at pressures >4 GPa in a diamond anvil cell using lithium fluoride and ice-VII as a quasi-hydrostatic pressure media. Temperature measurements are quantified using a ratiometric-thermometry approach involving a Boltzmann fit to excited states distribution through 4f-4f Stark-level transitions from the Yb3+ ions that occur between the 2F5/2 and 2F7/2 manifolds. At pressures between 7 and 12 GPa the YLF grains are observed to undergo a martensitic phase transition from a tetragonal scheelite phase (space group I41/a, Z = 4, No. 88) to a monoclinic fergusonite phase (space group I2/a, Z = 4, No. 15) which modifies the crys-tal field splitting of the ground- and excited- state manifolds, but is observed to not eliminate laser cooling. Solid-state laser refrigeration at extreme pressures could allow researchers to use rapid photothermal cycling to explore temperature-dependent properties of materials, including electronic-structure phase-transitions, without the need for external cryostats.</div

ОЦЕНКА ПОТЕРЬ БЮДЖЕТА КРАСНОЯРСКОГО КРАЯ ИЗ-ЗА НЕДОПОСТУПЛЕНИЯ НАЛОГОВ ОТ ПРЕДПРИЯТИЙ В СВЯЗИ С ВРЕМЕННОЙ НЕТРУДОСПОСОБНОСТЬЮ КУРЯЩИХ СОТРУДНИКОВ И СНИЖЕНИЯ ИНТЕНСИВНОСТИ ТРУДА ИЗ-ЗА ПЕРЕКУРОВ

The aim of the paper is to estimate Krasnoyarsk region budget losses due to the shortfalls of taxes from businesses related with a temporary disability of smoking employees and the reduction of labor intensity due to the smoking breaks in 2011.In our work we used the method of economic losses estimation, developed by Conference Board of Canada.The following results were obtained. The estimation of tax shortfalls due to a temporary disability of smoking employees and decrease of labor intensity due to smoking breaks was carried out. It was obtained that Krasnoyarsk region budget losses as a result of the tax shortfalls are equal to 532.8 million rubles – due to increased sick absence risks among smokers and 3 414.3 million rubles – due to the lack of workers on the workplace during smoking breaks. Thus, it was found that the total budget losses of Krasnoyarsk region in 2011 reach 0.34% of the gross regional product.The obtained results can be used for the assessments of the economic losses.DOI: http://dx.doi.org/10.12731/2218-7405-2013-7-22Целью данной работы являлось оценить потери бюджета Красноярского края, связанные с недопоступлением налогов из-за временной нетрудоспособности курящих сотрудников и снижения интенсивности труда из-за перекуров в 2011 г.В работе использовалась методика оценки экономических потерь, разработанная Совещательным Комитетом Канады (Conference Board of Canada, 2008 г.).Произведена оценка недопоступления налогов из-за временной нетрудоспособности курящих сотрудников и снижения интенсивности труда из-за перекуров. Установлено, что потери бюджета Красноярского края вследствие недопоступления налогов составляют 532,8 млн. рублей по причине дополнительных рисков пребывания на листе нетрудоспособности среди курильщиков и 3 414,3 млн. рублей – из-за отсутствия работников на рабочем месте во время перекуров. Суммарно – это потери 0,34% ВРП Красноярского края (по данным за 2011 год).Полученные результаты могут быть применены для оценки экономических потерь.DOI: http://dx.doi.org/10.12731/2218-7405-2013-7-2

Hydrothermal Synthesis and Solid-State Laser Refrigeration of Ytterbium-Doped Potassium Lutetium Fluoride (KLF) Microcrystals

Fluoride crystals, due to their low phonon energies, are attractive hosts of trivalent lanthanide ions for applications in upconverting phosphors, quantum information science, and solid-state laser refrigeration. In this article, we report the rapid, low-cost hydrothermal synthesis of potassium lutetium fluoride (KLF) microcrystals for applications in solid-state laser refrigeration. Four crystalline phases were synthesized, namely orthorhombic K2LuF5 (Pnma), trigonal KLuF4 (P3121), orthorhombic KLu2F7 (Pna21), and cubic KLu3F10 (Fm3m), with each phase exhibiting unique microcrystalline morphologies. Luminescence spectra and emission lifetimes of the four crystalline phases were characterized based on the point-group symmetry of trivalent cations. Laser refrigeration was measured by observing both the optomechanical eigenfrequencies of microcrystals on cantilevers in vacuum, and also the Brownian dynamics of optically trapped microcrystals in water. Among all four crystalline phases, the most significant cooling was observed for 10%Yb:KLuF4 with cooling of 8.6 $\pm$ 2.1 K below room temperature. Reduced heating was observed with 10%Yb:K2LuF5</sub

Band structure near the Dirac Point in HgTe quantum wells with critical thickness

Mercury telluride (HgTe) thin films with a critical thickness of 6.5 nm are predicted to possess a gapless Dirac-like band structure. We report a comprehensive study on gated and optically doped samples by magnetooptical spectroscopy in the THz range. The quasi-classical analysis of the cyclotron resonance allowed the mapping of the band dispersion of Dirac charge carriers in a broad range of electron and hole doping. A smooth transition through the charge neutrality point between Dirac holes and electrons was observed. An additional peak coming from a second type of holes with an almost density-independent mass of around 0.04m0 was detected in the hole-doping range and attributed to an asymmetric spin splitting of the Dirac cone. Spectroscopic evidence for disorder-induced band energy fluctuations could not be detected in present cyclotron resonance experiments

Judd-Ofelt Analysis of High Erbium Content Yttrium-Aluminum and Yttrium-Scandium-Aluminum Garnet Ceramics

The Er1.5Y1.5Al5O12 (Er:YAG) and (Er1.43Y1.43Sc0.14)(Sc0.24Al1.76)Al3O12 (Er:YSAG) ceramics have been characterized using the Judd-Ofelt (JO) theory. The line strengths and oscillator strengths of several transitions from the ground state 4I15/2 to excited state manifolds have been evaluated from transmittance spectra measured at room temperature (300 K). The JO parameters have been calculated, and the values of the radiative decays rate and the radiative lifetimes for the 4I13/2 excited state, and the luminescence cross-section of 4I15/2 → 4I13/2 in Er-doped ceramic samples have been established. We have traced the influence of Sc3+ inclusion on spectroscopic properties and crystal quality and estimate prospects of application in laser systems