Analysis and direct calculation of the energy migration interaction parameter in high concentration Nd3+ doped YAG laser crystal

The energy migration interaction parameter CDD in high concentration Nd3+ doped YAG laser crystal was estimated using the Yokota-Tanimoto (Y-T) model and the spectral overlap model (SOM) of Kushida, respectively. Firstly, the experimental luminescence decay curves of 4F3/2 state of Nd3+ ions in YAG laser crystal at room temperature for 2.0at.% and 3.0at.% Nd3+ concentrations reported by Mao were fitted successfully using the Y-T model, and the parameter CDD was obtained to be 1.50×10-39 cm6/s. Secondly, the parameter CDD was directly calculated using the spectral overlap model (SOM) of Kushida; CDD was calculated to be 2.73×10-39 cm6/s. By comparing the energy migration interaction parameter CDD with the energy transfer interaction parameter CDA (1.794×10-40 cm6/s), it was concluded that the energy migration rate between Nd3+ ions in YAG laser crystal was about 11 times larger than the energy transfer rate, and that energy migration played a very important role in high concentration Nd3+ -doped YAG laser crystal.     

Size dependence of up-conversion luminescence of NaYF₄:Yb³⁺/Tm³⁺

Tm3+/Yb3+ codoped NaYF4 microcrystals were synthesized using a hydrothermal method.The bright upconversion light was observed under 980 nm excitation.The upconversion luminescence was systematically investigated at different Yb3+ concentrations and different reaction temperatures and time.The sample with 60% Yb3+ concentration and reacting at 180 oC for 24 h possessed the highest luminescent efficiency.The higher luminescent efficiency was contributed to a large surface area.The large surface area induced the large vibration mode by absorbed H2O and CO2.The larger vibration mode could enhance the energy transfer efficiency from the excited Yb3+ to Tm3+ by the process of phonon assisted energy transfer.     

Up-conversion luminescence of Tm3+/Yb3+ co-doped oxy-fluoride glasses

The oxy-fluorosilicate glasses co-doped with Yb3+/Tm3+ were prepared.The absorption spectra were recorded.The Tm3+ ion showed two absorption bands,with one at 774 nm due to 1G4→3H6 transition and the other at 667 nm due to 1G4→3F4 transition.The energy transfer between Tm3+ ion and Yb3+ ion and the up-conversion fluorescence of Tm3+ ion were investigated using 980 nm LD excitation.The results showed that the blue and red emissions were three-photon absorption processes corresponding with 1G4→3H6 and 1G4→3F4...     

Tm3+-doped tellurite glass with Yb3+ energy sensitized for broadband amplifier at 1400-1700 nm bands

A kind of novel experiment was disclosed as it possessed two bands of fluorescence emission at 1.4 and 1.6 μm, which were per-fectly complimentary to the current C band of optic communication. The fluorescence was based on energy transfer and up-conversion proc-esses between Tm3+ and Yb3+ under direct pumping of 975 nm LD. The spectra and lifetimes of Tm3+ fluorescence in the tellurite glass were described. The corresponding fluorescence characteristics and energy migration process were analyzed by the method of lifetime and inten-sity comparison. The mechanism of the up-conversion based IR fluorescence was presented upon analyzing the multi-photon pumping proc-ess. The potential advantages of Tm3+/Yb3+ co-doped tellurite glass as amplifier material were concluded.     

Effect of RO （R=Ca, Sr, Ba, Zn or Pb） component on spectroscopic properties of Eu3＋ in RO-B2O3 glasses

Eu3+-doped binary borate glasses with different metal oxide components RO (R=Ca, Sr, Ba, Zn or Pb) were prepared by meltquenching technique. The fluorescent spectral properties of Eu3+in these glasses were experimentally studied. The analysis on the phonon sidebands (PSBs) indicated that RO component did not cause obvious change of the electron-phonon coupling constant (EPC). By inspecting the optical absorption edges it was found that RO could greatly affect the band gap energy, and the glass with PbO component revealed the smallest band gap energy, the glasses with ZnO, BaO and SrO showed similar band gap energy. The optical transition intensity parameters of Eu3+in all studied glasses were calculated, it was found that for each sample its value of2 was larger than that of 4 and 6, and the sample with PbO component exhibited the smallest2, but the λ values for ZBE, CBE, BBE and SBE were very similar. These results might be helpful for the design of borate glasses.     

Broadband near-infrared luminescence and energy transfer of Cr~(3+),Ce~(3+) co-doped Ca_2LuHf_2Al_3O_(12) phosphors

Broadband near-infrared phosphors are highly desirable for food testing.Targeted Ca₂LuHf₂Al₃O₁₂:Cr³⁺(CLHA:Cr³⁺) and Ca₂LuHf₂Al₃O₁₂:Ce³⁺,Cr³⁺(CLHA:Ce³⁺,Cr^(³⁺)) phosphors were synthesized by the conventional high-temperature solid state reaction.The CLHA:Cr³⁺phosphor,with a good thermal stability,shows a red shift owing to radiation reabsorption and non-radiative transition with increasing Cr³⁺content.For co-doped sample,the emission intensity of Cr³⁺can be enhanced by three times due to the energy transfer from Ce³⁺to Cr³⁺,which can be evidenced by a significant overlap between the PLE of Cr³⁺single-doped phosphor and the PL of Ce³⁺single-doped phosphor.In addition,the mechanism of energy transfer is identified as a quadrupole-quadrupole interaction according to decay Lifetime and Dexter’s energy transfer formula.The broadband NIR emission peaked at 775 nm of CLHA:Cr³⁺,Ce³⁺phosphor shows a bright prospect in nondestructive quality-control analysis systems for food.     

Cooperative energy transfer in Tm3＋and Yb3＋ co-doped phosphate glasses

An efficient near-infrared (NIR) quantum cutting (QC) in Tm3+ and Yb3+ co-doped phosphate glasses was demonstrated, which involved the emission of two NIR photons from an absorbed visible photon via a cooperative energy transfer (CET) from Tm3+ to Yb3+ ions. Judd-Ofelt (J-O) theory was used to calculate the intensity parameters ( 2 , 4 , 6 ), the radiative transition rates (Ar ), and radiative transition lifetime (τ rad ) of Tm3+ . Based on Inokuti-Hirayama’s model, the energy transfer processes were studied and results indicated that the energy transfer of the electric dipole-dipole (Edd) was dominant in this system. Quantum efficiency related to Yb 3+ concentration was calculated, and the maximum QE efficiency reached 169.8%.     

Fluorescence quenching by metal ions in lipid bilayers

Fluorescence quenching of perylene by Co2+ and Ni2+ ions has been investigated both below and above the phase transition temperature in small unilamellar DPPC vesicles. Classic F?rster type energy transfer was observed for perylene quenched by Co2+ ions below the phase transition when the effects of donor-donor energy transfer are taken into account. In the liquid crystalline phase a simple diffusion theory incorporating energy transfer was found to model the system well. For quenching by Ni2+ ions both above and below the phase transition temperature in lipid bilayers and in glycerol the data did not follow classic F?rster type energy transfer but indicated that an additional quenching mechanism was present. A mechanism other than F?rster behaviour was also observed for the quenching by Cr3+ ions in glycerol.     

基于“3060”目标的中国钢铁行业二氧化碳减排路径与潜力分析

 中国钢产量占世界总产量的56.7%,CO₂排放占世界钢铁总排放的72.5%,占全国碳排放的15%。为实现“3060”目标,对国内外钢铁行业现状、减碳路径与潜力进行了分析,探讨了短流程、能源结构调整和余能利用对碳减排的贡献度及碳税对减碳的影响。进出口方面,中国2020年钢铁出口量占世界总出口量的12.8%,占中国钢铁产量的4.8%,以满足内需为主,适当增加废钢进口量可减少碳税,同时降低中国对铁矿石的依赖度,提高中国在原材料市场的议价权;当短流程占比提高至30%时,预计每年减碳3.8亿t,对2030年减碳贡献率为2.09%,减少碳税152亿美元;采取70%废钢+30%DRI电炉炼钢流程时,可实现碳减排0.7亿t,对2030年的减碳贡献达0.39%,减少28亿美元碳税。实施氧气高炉技术、氢能冶炼技术及CCUS技术,可减碳49.55亿t,对2030年减碳贡献率为24.6%,减少碳税1 982亿美元。其中,氢能冶炼减碳效果最显著,可减碳42.63亿t,对2030年减碳贡献率为20.79%,减少碳税1 705.2亿美元,其次为氧气高炉,可减碳3.42亿t,对2030年减碳贡献率为1.88%,减少碳税136.8亿美元。若高品位余能全部得到有效利用,预计可减碳1.39亿~1.4亿t,对2030年减碳贡献率为0.77%,减少碳税55.84亿美元。当低品位余能利用率从30%提高至50%时,预计减碳0.66亿t,贡献率为0.36%,减少碳税26.4亿美元。为实现“3060”目标,中国钢铁行业短期内可提高短流程覆盖率,同时加速研发氧气高炉、氢能冶炼、储能、余能梯级利用等减碳新技术。     

Synthesis and Characterization of Lanthanide Complexes Involving Cyclopentadienyl and Benzohydroximic Acid Ligand

Ｉｎｇｅｎｅｒａｌ,ｈｙｄｒｏｘｉｍｉｃａｃｉｄｓ (ＲＣＯＮ ＨＯＨ)ａｒｅｗｅａｋｏｒｇａｎｉｃａｃｉｄｓ .ＴｈｉｓｃｌａｓｓｏｆｏｒｇａｎｉｃｃｏｍｐｏｕｎｄｓｃｏｎｔａｉｎｉｎｇｔｈｅｒｅａｃｔｉｖｅｇｒｏｕｐＣＯＮＨＯＨ ,ｋｎｏｗｎａｓｔｈｅｈｙｄｒｏｘｉｍｉｃａｃｉｄｓ,ｈａｖｅｂｅｅｎｗｉｄｅｌｙｓｔｕｄｉｅｄｂｙｏｒｇａｎｉｃｃｈｅｍｉｓｔｓ.Ｔｈｅｈｙｄｒｏｘｉｍｉｃａｃｉｄｓａｒｅｃｈｅｌａｔｅｌｉｇａｎｄｓｆｏｒｍａｎｙｍｅｔａｌｓ .Ｔｈｅｙａｒｅｗｉｄｅｌｙｕｓｅｄａｓｃｈｅｌ…     

Luminescence and Energy Transfer Properties of Ca2Gd8(SiO4)6O2∶ A (A=Pb2+,Tm3+)Phosphors

Ca2Gd8(SiO4)6O2∶ A(A=Pb2 , Tm3 )phosphors were prepared through the sol-gel process. X-ray diffraction(XRD), scanning electron microscopy(SEM)and photoluminescence spectra were used to characterize the resulting phosphors. The results of XRD indicate that the phosphors crystallized completely at 1000 ℃. SEM study reveals that the average grain size is 300～1000 nm. In Ca2Gd8(SiO4)6O2∶ Tm3 phosphors, the Tm3 shows its characteristic blue emission at 456 nm(1D2-3F4)upon excitation into its 3H6 - 1D2(361 nm), with an optimum doping concentration of 1mol% of Gd3 in the host lattices. In Ca2Gd8(SiO4)6O2∶ Pb2 , Tm3 phosphors, excitation into the Pb2 at 266 nm(1S0-3P1)yields the emissions of Gd3 at 311 nm(6P-8S)and Tm3 at 367 nm(1D2 -3H6)and 456 nm(1D2-3F4), indicating that energy transfer processes of Pb2 - Gd3 and Pb2 - Tm3 have occurred in the host lattices.     

Investigation on energy transfer from Er3+ to Nd3+ in teilurite glass

A study of energy transfer of Er3+/Nd3+ codoped tellurite glasses was presented. By Nd3+ co-doping, both the Er3+ green emission corresponding to the Er3+: (4S3/2,2H11/2)→4I15/2 transitions and the red emission corresponding to the Er3+: 4F9/2→4I15/2 transitions were quenched. The energy transfer mechanism between Er3+ and Nd3+ was discussed based on their energy level characteristics. The interaction parameters, CD-A, for the energy transfer processes from Er3+ to Nd3+ in tellurites glass were calculated. Finally, the resonant transfer Er3+: 4I9/2→Nd3+: (4F5/2, 2H9/2) was proposed to be the most probable microscopic process to occur in contrast with the other processes.     

Photoluminescence studies of Eu2+-Yb3+ co-doped BaMgAl10O17 phosphor synthesized by the combustion method

BaMgAl10O17:Eu2+,Yb3+ was investigated as a possible quantum cutting system to enhance solar cells efficiency. Phosphors were synthesized by combustion method and composed of nanorods. Photoluminescence spectra showed that Eu in the sample was reduced to bi-valence while Yb remained trivalence. Through a cooperative energy transfer process, the obtained powders exhibited both blue emission of Eu2+ (around 450 nm) and near infrared emission of Yb3+ (around 1020 nm) under broad band excitation (250-410 nm) originating from 4f→5d transition of Eu2+. Energy transfer phenomenon between the sensitizer Eu2+ and the activator Yb3+ was investigated via the lumines-cent spectra and the decay curves of Eu2+ with different Yb3+ concentrations. Results indicated that energy transfer efficiency from Eu2+ to Yb3+ was not high. The poor efficiency can be explained by the long distance between rare earth ions.     

Efficient improvement of 2.7 μm luminescence of Er~(3+):oxyfluoride glass containing gallium by Yb~(3+) ions codoping

Mid-infrared laser materials with low phonon energy have significant applications. However, the development of available glass systems for high-power laser gain medium have posed a great challenge.Therefore, we investigated the 2.7 μm spectroscopic properties of Er~(3+)/Yb~(3+) -codoped oxyfluoride glass containing gallium, which were prepared by typically melting and quenching methods. The 2.7 μm luminescence properties of the Er~(3+)/Yb~(3+)-codoped oxyfluoride glass containing gallium were recorded by a 980 nm laser diode. The Judde Ofelt parameters, decay curves, emission cross section, energy transfer efficiency and quantum efficiency were calculated. The maximum emission cross section of YbFGa-0.5 is 1.63 × 10~(-20) cm~2 by 980 nm excitation. The energy transfer efficiency is calculated to be77.8% for the YbFGa-0.5 glass around 2700 nm. The quantum efficiency at 1530 nm is 65.6%. The result reveals that the best doping concentration ratio of Er~(3+):Yb~(3+) ions is 1:0.5, and suggests an effective energy transfer from Yb~(3+) to Er~(3+) ions.     

Enhanced 1-5 μm near-and mid-infrared emission in Ho~(3+)/Yb~(3+)codoped TeO_2-ZnF_2 oxyfluorotellurite glasses

Intense 1-5 μm infrared emission from near-to mid-infrared was obtained from Ho~(3)+/Yb~(3+)codoped TeO_2-ZnF_2 oxyfluorotellurite glasses which were prepared by melt-quenching method under the 980 nm LD excitation,and the emission intensity can be enhanced with the increase of ZnF_2 content.Judd-Ofelt analysis was used to evaluate the radiative transition parameters of the excited levels according to the absorption spectra.The stimulated emission cross section of ~5 I6→~5 I_8(1.2 μm),~5 I7→~5 I_8(2.0μm),~5 I_6→~5 I_7(2.85 μm) and ~5 I_5→~5 I_6(4.0 μm) transitions were calculated to reach 0.639 × 10~(-20),0.760 ×10~(-20),0.985×10 20 and 0.484 × 10~(-20) cm~2,respectively.The energy transfer coefficients(C_(DA)) are enhanced with the increase of ZnF2 content and phonon contribution ratios of phonon assisted energy transfer process between Ho~(3+) and Yb~(3+)were figured out.Our results demonstrate that these TeO_2-ZnF_2 glasses,which possess good thermal stability and transparency,low phonon energy(about 600 cm~(-1)),excellent near-and mid-infrared emission in the range of 1-5 μm wavelength,would be promising material for infrared optical fibers and infrared lasers.     

Down- and up-conversion processes in Nd3+/Yb3+ co-doped sodium calcium silicate glasses with concomitant Yb2+ assessment

Novel Nd³⁺/Yb³⁺ co-doped sodium calcium silicate glasses were prepared by melting quenching method:Spectroscopic study was carried out as a function of doping content by fixing sensitizer(Nd³⁺) concentration to 0.2 mol% and adjusting activator(Yb³⁺) from 0 to 1.0 mol%.The energy transfer(ET)mechanisms between Nd³⁺and Yb³⁺ are discussed based on their energy levels and excitation powerdependence emission intensity.Results show that...     

Size dependence of up-conversion luminescence of NaYF4:Yb3+/Tm3+

Tm³⁺/Yb³⁺ codoped NaYF₄ microcrystals were synthesized using a hydrothermal method. The bright upconversion light was observed under 980 nm excitation. The upconversion luminescence was systematically investigated at different Yb³⁺ concentrations and different reaction temperatures and time. The sample with 60% Yb³⁺ concentration and reacting at 180 °C for 24 h possessed the highest luminescent efficiency. The higher luminescent efficiency was contributed to a large surface area. The large surface area induced the large vibration mode by absorbed H₂O and CO₂. The larger vibration mode could enhance the energy transfer efficiency from the excited Yb³⁺ to Tm³⁺ by the process of phonon assisted energy transfer.     

Energy transfer processes from Yb3＋ to Ln3＋ （Ln=Er or Tm） in heavy metal glasses

Heavy metal glasses doubly doped with Yb3+ and Ln3+ ions(Ln=Er or Tm) were studied. Glass host matrices were limited to lead borate glass and lead germanate glass. Efficient resonant(Yb3+-Er3+) and non-resonant(Yb3+-Tm3+) energy transfer was observed for the studied systems. Near-infrared luminescence spectra at 1.53 μm(Er3+) and 1.9 μm(Tm3+) were detected under excitation of Yb3+ by 975 nm diode laser line. They corresponded to 4I13/2→4I15/2(Er3+) and 3F4→3H6(Tm3+) transitions of rare earth ions, respectively. The unusual large spectral linewidth nearly close to 110 nm for 4I13/2→4I15/2 transition of Er3+ ions in lead borate glass was obtained, whereas long-lived near-infrared luminescence at 1.53 μm was detected in lead germanate glass. Quite different situation was observed for Yb3+-Tm3+ doubly doped glasses. In contrast to lead borate glass, near-infrared(3F4→3H6) luminescence spectra were registered for Tm3+ ions in lead germanate glasses, only. These phenomena strongly depended on stretching vibrations of glass host, which was confirmed by FT-IR spectroscopy.     

Magnetically aligned phospholipid bilayers with positive ordering: a new model membrane system

A stable smectic phospholipid bilayer phase aligned with the director parallel to the magnetic field can be generated by the addition of certain trivalent paramagnetic lanthanide ions to a bicellar solution of dimyristoylphosphatidylcholine (DMPC) and dihexanoylphosphatidylcholine (DHPC) in water. Suitable lanthanide ions are those with positive anisotropy of their magnetic susceptibility, namely Eu3+, Er3+, Tm3+, and Yb3+. For samples doped with Tm3+, this phase extends over a wide range of Tm3+ concentrations (6-40 mM) and temperatures (35-90 degrees C) and appears to undergo a transition from a fluid nematic discotic to a fluid, but highly ordered, smectic phase at a temperature that depends on the thulium concentration. As a membrane mimetic, these new, positively ordered phospholipid phases have high potential for structural studies using a variety of techniques such as magnetic resonance (EMR and NMR), small-angle x-ray and neutron diffraction, as well as optical and infrared spectroscopy.     

Energy transfer from Tb³⁺ to Eu³⁺ in zinc lead borate glass

In order to sensitize the luminescence of Eu3+ ions in heavy metal glass,zinc lead borate glass samples containing various concentrations of Eu3+ and Tb3+ ions were prepared to study the Tb3+ to Eu3+ non-radiative energy transfer phenomena.Energy level structures of Tb3+ and Eu3+ ions were plotted to show the excitation and energy transfer routes.Efficient energy transfer from Tb3+ to Eu3+ was observed and studied qualitatively in terms of doping concentrations.The sensitization turned out to be less effective than expected.Further studies to characterize the oxidation of Tb3+ into tetravalent state and to examine the mechanism of energy transfer are proposed.