PEG Assisted Hydrothermal Synthesis of β-Na YF_4:Yb~(3+),Er~(3+) Microrods for Upconversion Photoluminescence Display

β-Na YF4:Yb3+,Er3+ microrods with average length of 10 μm and diameter of 2.5 μm were synthesized through hydrothermal method. Based on the obtained microrods, transparent and flexible film with upconversion luminescence property was prepared through inorganic-organic composition method by using co-polymerization product of isobornylmethacrylate and urethane acrylate as the polymer substrate. The prepared film shows excellent optical transmission in the visible region with average transmission of 81.3% at high doping concentration(2 wt%) of β-Na YF4:Yb3+,Er3+ microrods. By directing and moving NIR laser beam toward the prepared film with high scanning speed, visible light is effectively emitted and various images are able to display.     

Growth and Optical Properties of Sr_6YbSc(BO_3)_6 Crystal

1INTRODUCTION As is well known,the Yb3 ion has some advan-tages in comparison with Nd3 as laser active ion,for it has only two manifolds,i.e.,the ground2F7/2state and the excited2F5/2state.There is no excited state absorption reducing effective laser cross-section,no concentration quenching,no up-conversion,and three or four times longer emission lifetime than Nd3 ion.Yb3 ion exhibits a strong and broad ab-sorption band at ca.970nm and can be easily pumped with InGaAs diode lasers.The …     

In situ spectroelectrochemical behaviour of nanocrystalline TiO_2 thin films electrode fabricated by pulsed laser deposition

Nanocrystalline titanium oxide thin films have been successfully deposited on ITO coated glass by pulsed laser ablation of metallic Ti target in O_3/O_2 ambient gases. The intercalation of Li ions in the anatase TiO_2 film electrode is examined by cyclic vohammetry. The electrochromic behaviour of TiO_2 electrode is investigated by in-situ visible transmittance measurement, and two absorption bands at 420 and 650 nm are observed. The absorption falling and rising in color changing with excellent revisibility is relative to the insertion and deintercalation processes of Li ion. These resuits suggest that nanocrystalline titanium oxide films fabricated by pulsed laser deposition exhibit excellent spectroelectrochemical property.     

Growth and Spectral Properties of Nd^3＋ Doped KLa（MoO4）2 Crystal

1 INTRODUCTION There has been an increasing interest in the re- search of diode-pumped solid-state lasers in recent years because of the rapid development of high power diode lasers. The absorption peak of Nd3 ions at about 800 nm corresponding to 4I9/2→ 2H9/2 tran- sition is suitable for commercial laser diode GaAlAs pumping[1]. KLa(MoO4)2 is a kind of disordered crystalline host for lasing rare-earth ions[2], and it belongs to Scheelite (CaWO4) structure[3]. The disorder derives…     

On-chip classification of micro-particles using laser light scattering and machine learning

The rapid detection of microparticles exhibits a broad range of applications in the field of science and technology. The proposed method differentiates and identifies the 2 μm and 5 μm sized particles using a laser light scattering. The detection method is based on measuring forward light scattering from the particles and then classifying the acquired data using support vector machines. The device is composed of a microfluidic chip linked with photosensors and a laser device using optical fiber....     

A V-shaped spectroscopic cell for FTIR measurements

A V-shaped spacroscopic cell（V-cell） was constructed using two CaF₂ optical plates for FTIR light transparent measurements in the range of 4000-1000 cm^-1.The spectrum of ethanol was characterized with the standard spectra,excellent fitting was achieved with a bottom-width correction method.The principle of the V-cell was discussed,giving equations for the data interpretation.It shows that the V-cell is an auto-focus type spectroscopic cell,which can effectively avoid absorption saturation with amplifications for weak absorption bands.The V-cell design is simple and effective,easy to operate,suitable for applications in liquid samples with high absorption bands,willing to have broad application prospects.     

Chlorophyll sensitized BiVO4 as photoanode for solar water splitting and CO2 conversion

Converting solar energy into valuable hydrogen and hydrocarbon fuels through photoelectrocatalytic water splitting and CO_2 reduction is highly promising in addressing the growing demand for renewable and clean energy resources. However, the solar-to-fuel conversion efficiency is still very low due to limited light absorption and rapid bulk recombination of charge carriers. In this work, we present chlorophyll(Chl) and its derivative sodium copper chlorophyllin(ChlCuNa), as dye sensitizers, modified BiVO_4 to improve the photoelectrochemical(PEC) performance. The photocurrent of BiVO_4 is surprisingly decreased after a direct sensitization of Chl while the sensitization of ChlCuNa obviously enhances photocurrent of BiV04 electrodes by improved surface hydrophilicity and extended light absorption.ChlCuNa-sensitized BiV04 achieves an improved H_2 evolution rate of 5.43 μmol h~(-1) cm~(-2) in water splitting and an enhanced HCOOH production rate of 2.15 μmol h~(-1) cm~(-2) in CO_2 PEC reduction, which are1.9 times and 2.4 times higher than pristine BiVO_4, respectively. It is suggested that the derivative ChlCuNa is a more effective sensitizer for solar-to-fuel energy conversion and CO_2 utilization than Chl.     

Gold Nanoparticle-based Colorimetric Assay for Determination of Lead(Ⅱ) in Aqueous Media

The authors presented a simple colorimetric assay for the detection of toxic heavy metal lead(Ⅱ) ion(Pb2+).Pentapeptide,cysteine-alanine-leacine-asparagine-asparagine(CALNN),functionalized gold nanoparticles(GNPs) were aggregated in the presence of the divalent metal ion in solution by an ion-templated chelation process,which caused an easily measurable change in the absorption spectrum of the particles.Typically,mono-dispersing GNPs exhibit an absorption band at 522 nm,corresponding to a red color solution,while aggregated GNPs have it at longer wavelengths,corresponding to a purple or blue color solution.The chelation/aggregation process is reversible via the addition of a strong metal ion chelator such as EDTA.Highly selective and sensitive detection of Pb2+ in aqueous solution is thus provided.A detection limit of 0.1 μmol/L of Pb2+ was demonstrated.     

STUDIES ON RARE EARTH METAL COMPLEXES OF AMINO ACIDS. THE SYNTHESIS AND CRYSTAL STRUCTURE OF TE-TRAKIS ( ALANINE ) OCTAAQUODILANTHANIDE HEXAPER-CHLORATE [Ln_2(Ala)_4(H_2O)_8]*(ClO_4)_6(Ln = Er~(3+)and Eu~(3+),Ala=CH_3CH(~+NH_3)COO~-)

<正> Complex [Er2(Ala)4(H2O)8]·(ClO4)6, 1, Mr = 1431. 8, mono-clinic, space group C2/c with cell parameters a= 18. 21(1), 6 = 14. 67(2), c=17. 19(3)(?), β=101. 60(8)°, V = 4495(4)(?)3, Dc=2.11g/cm3, Do = 2. 09g/cm3, Z = 4, F (000) = 2808, μ= 42. 30cm-1; Complex [Eu2(Ala)4(H2O)8]·(ClO4)6, 2, Mr = 1401.4, monoclinic, space group C2/c, a = 18. 16(4) , b = 14.52(2), c=17. 35(1)(?), β=102. 3(1)°, Z = 4, V= 4468(11)(?)3. The structure of complex 1 is refined by full-matrix least - squares method with 3348 observed reflections (I≥3σ (I)) to R = 0. 048 and Rw= 0.060. The two erbium ions in the dimeric complex cation [Er2(Ala)4(H2O)8]]6+ are connected by four bridging carboxylato groups, each pair of the carboxylato groups is coplanar with the two Er(III) ions and the dihedral angle between the two planes is 91. 42*. Each Er3+ion is coordinated by four carboxylato oxygen atoms and four water oxygen atoms, assuming a square antiprism arrangment. The alanine exists in the form of CH3CH (+NH3) COO- , and the mo     

Synthesis,structure and magnetism of a novel Cu_4~ⅡTi_5~Ⅳ heterometallic cluster

A nonanuclear Cu_4~ⅡTi_5~Ⅳ heterometallic cluster,[Ti_5 Cu_4 O_6(ba)_(16)](1,Hba=benzoic acid) was synthesized in one-pot reaction under the solvothermal condition.The metallic skeleton 1 contains a Ti_5 core constructed from two vertex-shared Ti_3 triangles and four separated Cu atoms outside which are connected together by μ_3-O~2 ions.Total 16 ba ligands adopt μ_2-η~1:η~1 coordination mode to protect the overall hetero metallic co re.Due to the unique d-d transitions of Cu~Ⅱ ion,the reflectance spectrum of 1 displays broad and strong absorption towards visible light extending to the near-infrared region.Moreover,1 shows almost purely paramagnetic behavior with the presence of weak antiferromagnetic interactions at low temperatures.     

Growth and Spectroscopic Characteristics of Yb3＋：LiGd（WO4）2 Crystal

The Yb3+:LiGd(WO4)2 crystal with the dimension of Φ15×35 mm3 was grown by Czochralski technique. The spectroscopic characterization and fluorescence dynamics of Yb3+ in Yb3+:LiGd(WO4)2 crystal were investigated. The Yb3+:LiGd(WO4)2 crystal exhibits a broad absorption band centered near 975 nm with the linewidths of 16 and 11 nm and maximal absorption cross-section of 3.60 × 10-20 and 2.90 × 10-20 cm2 for π- and σ-polarization, respectively. The emission broadband has an FWHM of 47 and 45 nm with the emission cross sections of 3.92 × 10-20 and 3.34 × 10-20 cm2 at 1020 nm for π- and σ-polarization, respectively. The measured fluorescence lifetime is 398 μs. The blue light emission around 480 nm through cooperative upconversion from the de-excitation of excited Yb3+-Yb3+ pairs at 4 K was observed under 932-nm excitation and demonstrated.     

Investigation of thermal stability and spectroscopic properties in Er3+/Yb3+ co-doped niobic tungsten tellurite glasses

A series of novel Er3+/Yb3+ co-doped 75TeO2-(25-x)Nb2O5-xWO3 (TNW: x=0, 3, 6, 9, 12, and 15 mol%) glasses have been prepared. Effect of WO3 on the thermal stability and spectroscopic properties of Er3+/Yb3+ co-doped niobic tellurite glasses have been investigated. With WO3 content increasing from 0 to 15 mol%, the fluorescence full width at half maximum (FWHM), the peak of stimulated emission cross-section (sigmaepeak), the measured lifetime (taum), and quantum efficiency (eta) change from 71 nm, 8.47x10(-21) cm2, 2.86 ms, 84.1% to 76 nm, 7.22x10(-21) cm2, 3.14 ms, 88.9%, respectively. The FWHM and sigmaepeak of Er3+ ions in different glass hosts were compared; the obtained data reveals that this new TNW4 glass may be a potentially useful candidate material host for broadband amplifiers.     

Optical transitions of Er3+/Yb3+ codoped TeO2-WO3-Bi2O3 glass

Optical absorption and emission properties of the Er3+/Yb3+ codoped TeO2-WO3-Bi2O3 (TWB) glass has been investigated. The transition probabilities, excited state lifetimes, and the branching ratios have been predicted for Er3+ based on the Judd-Ofelt theory. The broad 1.5 microm fluorescence was observed under 970 nm excitation, and its full width at half maximum (FWHM) is 77 nm. The emission cross-section is calculated using the McCumber theory, and the peak emission cross-section is 1.03 x 10(-21) cm2 at 1.531 microm. This value is much larger than those of the silicate and phosphate glasses. Efficient green and weak red upconversion luminescence from Er3+ centers in the glass sample was observed at room temperature, and the upconversion excitation processes have been analyzed.     

Yb3+/Tm3+掺杂的NaY(WO4)2纳米晶的制备及发光特性

以聚乙二醇为配位剂,用水热法制备出纳米级上转换发光粉Yb3+和Tm3+共掺杂的NaY(WO4)2。研究了不同cYb/cTm对上转换发光强度的影响,实验表明当cYb/cTm=5∶1时,上转换发光强度最强。用XRD,SEM确定了Yb3+和Tm3+共掺杂的NaY(WO4)2是四方晶系,其粒径在25~35 nm范围,且分散均匀。用980 nm半导体激光器(LD)对其进行激发,在室温下观察到了365 nm附近紫外发射峰、456 nm,476 nm附近的蓝光发射峰和648 nm附近的红光发射峰,分别对应于Tm3+离子的1D2→3H6,1D2→3F4,1G4→3H6和1G4→3F4的跃迁。根据泵浦功率与发光强度的关系得出紫外发射峰、蓝光和红光发射均为双光子过程。     

Spectral properties of Er3+/Yb3+ codoped tungsten-tellurite glasses

The spectral properties of Er3+/Yb3+ codoped tungsten-tellurite (WT) glasses have been investigated. The measured absorption spectra are analyzed by Judd-Ofelt theory. The compositional change of intensity parameter omega2 is attributed to the change in the covalency between the Er3+ and oxygen ions, the asymmetry in the local structures around the Er3+ ions can be neglected. The lifetimes of 4I(13/2) level of Er3+ in WT glasses are measured and comparable with other TeO2-based glasses. The stimulated emission cross-section is calculated based on McCumber theory. The fluorescence full width at half maximum (FWHM) and the emission cross-section (sigma(peak)) of the 4I(13/2) --> 4I(15/2) transition of Er3+ in different glass hosts have been compared. The suitability of such WT glasses as host materials for 1.5 microm broadband amplification is discussed.     

Spectroscopic properties of Er3+, Yb3 + and Er3 + /Yb3+ doped metaphosphate glasses

The absorption and emission spectroscopies of Er3+ doped and Er3+/Yb3+ codoped Ca(PO3)2, Sr(PO3)2 and Ba(PO3)2 glasses have been studied. From the Judd-Ofelt intensity parameters, the spontaneous emission probabilities of some relevant transitions and the radiative lifetimes of several excited states of Er3+ have been calculated. The decay curves of the Er3+ emission at 1.5 microm have been measured at different temperatures. The data have been fitted using a stretched exponential function and the obtained experimental lifetimes have been compared with the calculated radiative lifetimes. The difference between the experimental and calculated lifetimes is attributed to the presence of traces of OH groups in the host glasses. The absolute OH content in some glasses has been determined from the infrared spectra. The emission spectra at 1.5 microm of the Er3+ ion in the codoped glasses have been measured at different temperatures. The integrated emission intensities decrease significantly on passing from room temperature to 13 K, suggesting a temperature dependence of the rate of the energy transfer process between Yb3+ and Er3+.     

Mn~(2+)掺杂NaBiF_4∶Yb/Er体系的可调控上转换发光

采用溶剂热法制备了不同Mn~(2+)掺杂量的NaBiF_4∶Yb/Er/Mn上转换发光体系,研究了其形貌、晶相、上转换发光性能随Mn~(2+)掺杂量的变化,并探讨了该体系的能量传递机理.实验结果表明,Mn~(2+)的掺杂不会引起NaBiF_4从六方相转变为立方相,但会增大其尺寸;同时在NaBiF_4体系中,Mn~(2+)可以与Er~(3+)进行能量传递,使红光发射得到增强,并且随着Mn~(2+)浓度的增加,红/绿光发射强度比也会随之增大.此外,还考察了NaBiF_4∶Yb/Er/Mn体系的变温发射光谱,发现当温度升高时,红/绿光强度比以及520 nm绿光与540 nm绿光发射强度比都总体上呈增大趋势.     

Yb3+敏化宽波带掺Er3+氟磷酸盐玻璃的发光性质及Judd-Ofelt理论研究

采用高温熔融法制备了一种新的Er3+/Yb3+共掺氟磷酸盐玻璃,测试和分析了其密度、吸收光谱以及荧光光谱,讨论了Er3+离子和Yb3+离子对光谱性质的影响.根据Judd-Ofelt理论计算了玻璃中Er3+离子的强度参数Ωt(t=2,4,6),分别为Ω2=4.36×10-20cm2,Ω4=1.35×10-20cm2,Ω6=0.79×10-20cm2,以及Er3+离子4I13/2能级荧光寿命τm=8.26ms.主发射峰1.53μm处半高宽(FWHM)为68nm.根据McCumber理论计算了Er3+的受激发射截面σe=8.5×10-21cm2.比较了不同玻璃基质中Er3+离子的光谱特性,结果表明:Er3+/Yb3+双掺氟磷酸盐玻璃在1.53μm附近具有较宽的半高宽和较大的受激发射截面,是一种高增益掺铒光纤放大器的理想介质材料.     

Controllable synthesis and tunable luminescence properties of Y2(WO4)3:Ln3+ (Ln = Eu, Yb/Er, Yb/Tm and Yb/Ho) 3D hierarchical architectures

Yttrium tungstate precursors with novel 3D hierarchical architectures assembled from nanosheet building blocks were successfully synthesized by a hydrothermal method with the assistance of sodium dodecyl benzenesulfonate (SDBS). After calcination, the precursors were easily converted to Y(2)(WO(4))(3) without an obvious change in morphology. The as-prepared precursors and Y(2)(WO(4))(3) were characterized by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and high-resolution transmission electron microscopy (HRTEM), and photoluminescence (PL) spectra, respectively. The results reveal that the morphology and dimensions of the as-prepared precursors can be effectively tuned by altering the amounts of organic SDBS and the reaction time, and the possible formation mechanism was also proposed. Upon ultraviolet (UV) excitation, the emission of Y(2)(WO(4))(3):x mol% Eu(3+) microcrystals can be tuned from white to red, and the doping concentration of Eu(3+) has been optimized. Furthermore, the up-conversion (UC) luminescence properties as well as the emission mechanisms of Y(2)(WO(4))(3):Yb(3+)/Ln(3+) (Ln = Er, Tm, Ho) microcrystals were systematically investigated, which show green (Er(3+), (4)S(3/2), (2)H(11/2)→(4)I(15/2)), blue (Tm(3+), (1)G(4)→(3)H(6)) and yellow (Ho(3+), (5)S(2)→(5)I(8)) luminescence under 980 nm NIR excitation. Moreover, the doping concentration of the Yb(3+) has been optimized under a fixed concentration of Er(3+) for the UC emission of Y(2)(WO(4))(3):Yb(3+)/Er(3+).     

Preparation and photoluminescence properties of RE:Na3La9O3(BO3)8 (RE=Er, Yb) crystals

Using Na₂CO₃-H₃BO₃-NaF as fluxes, transparent RE:Na₃La₉O₃(BO₃)₈ (abbr. RE:NLBO, RE=Er, Yb) crystals have been grown by the top seed solution growth (TSSG) method. The X-ray powder diffraction analysis shows that the RE:NLBO crystals have the same structure with NLBO. The element contents were determined by molar to be 0.64% Er³⁺ in Er:NLBO, 2.70% Yb³⁺ in Yb:NLBO, respectively. The polarized absorption spectra of RE:NLBO have been measured at room temperature and show that both Er:NLBO and Yb:NLBO have a strong absorption bands near 980 nm with wide FWHM (Full Wave at Half Maximum) (21 nm for Er:NLBO and 25 nm for Yb:NLBO). Fluorescence spectra have been recorded. Yb:NLBO has the emission peaks at 985 nm, 1028 nm and 1079 nm and the emission peak of Er:NLBO is at 1536 nm. Spectral parameters have been calculated by the Judd-Ofelt theory for Er:NLBO and the reciprocity method for Yb:NLBO, respectively. The calculated values show that Er:NLBO is a candidate of 1.55 μm laser crystals and Yb:NLBO is a candidate for self-frequency doubling crystal.