Enhancement of green emission by the codoping U . 3＋ A＋ （A - Li, Na, K） in Ca2 O3CI.Tb phosphor

Tb3＋-doped Ca2BO3C1 compounds with different charge compensation approaches are synthesized by a hightemperature solid-state reaction method, and the luminescent properties and Commission Internationale de l＇Eclairage （CIE） chromaticity coordinates are systematically characterized. Ca2BO3Cl：Tb3＋ can produce green emission under 376 nm radiation excitation. With codoped A＋ （A = Li, Na, K） as charge compensators, the relative emission intensities of Ca2BO3Cl：Tb3＋ are enhanced by about 1.61, 1.97, and 1.81 times compared with those of the direct charge balance, which is considered to be due to the effect of the difference in ion radius on the crystal field. The CIE chromaticity coordinates of Ca2BO3CI：Tb3＋, A＋ （A = Li, Na, K） are （0.335, 0.584）, （0.335, 0.585）, and （0.335, 0.585）, corresponding to the hues of green. Therefore, A＋ （A = Li, Na, K） may be the optimal charge compensator for Ca2BO3Cl：Tb3＋.     

Sr3Bi（PO4）3：Eu^2＋ Luminescence,Concentration Quenching and Crystallographic Sites

A blue emitting phosphor Sr3Bi（PO4）3：Eu2＋ is synthesized luminescent property is investigated. Sr3Bi（PO4 ）3 ：Eu^2＋ can by a high-temperature solid state method, and its create blue emission under the 332 radiation excitation, and the prominent luminescence in blue （423nm） due to the 4fSd^1→4f^7 transition of the Eu^2＋ ion. The crystallographic sites of the Eu^2＋ ion in Sr3Bi（PO4）3 are analyzed, and the 420 and 440 nm emission peaks of the Eu^2＋ ion are assigned to the nine-coordination and eight-coordination, respectively. The emission intensity of Sr3Bi（PO4）3：Eu^2＋ is influenced by the Eu^2＋ doping content, and the concentration quenching effect is observed. The quenching mechanism is the dipole-dipole interaction, and the critical distance of energy transfer is calculated by the concentration quenching method to be approximately 1.72nm.     

Photoluminescence characteristics and energy transfer between Bi~（3＋） and Eu~（3＋） in Na_2O–CaO–GeO_2–SiO_2 glass

We report the photoluminescence（PL） of Eu^3＋-doped glass with Bi^3＋as a sensitizer. The specific glass system with the strong enhancement of the red emission of Eu3＋is obtained by adding a small number of Bi3＋ions instead of increasing the Eu^3＋ concentration. The emission band of Bi3＋overlaps with the excitation band of Eu^3＋ and the lifetime decay curves,resulting in a very efficient energy transfer from Bi^3＋ to Eu^3＋. The probability of energy transfer is strongly dependent on Bi^3＋ concentration. In addition, the intensity of 4f–4f transition is much stronger than that of a charge-transfer（CT） band in the excitation spectrum, which indicates that the Na2O–Ca O–Ge O2-Si O2 glass is a suitable red-emitting phosphor with high stability as a candidate for light-emitting diodes（LEDs）.     

Quasi-classical trajectory investigation on the stereodynamics of Li ＋ DF（v=1-6,j=0）→LiF＋D reaction

In this paper, the stereodynamics of Li ＋ DF → Li F ＋ D reaction is investigated by the quasi-classical trajectory（QCT）method on the ^2A＇ potential energy surface（PES） at a relatively low collision energy of 8.76 kcal/mol. The scalar properties of the title reaction such as reaction probability and cross section are studied with vibrational quantum number of v = 1–6. The product angular distributions P（θr） and P（φr） are presented in the same vibrational level range. Moreover, two polarization-dependent generalized differential cross sections（PDDCSs）, i.e., the PDDCS00 and PDDCS22＋are calculated as well. These stereodynamical results demonstrate sensitive behaviors to the vibrational quantum numbers.     

Upconversion Luminescence Dynamics in Er^3＋/Yb^3＋ Codoped Nanocrystalline Yttria

The upconversion luminescence and dynamics in Er^3＋ /Yb^3＋ codoped nanocrystalline yttria （7-65 nm） are studied under 980-nm pulsed laser excitation, It is found that the red emission of ^4F9/2-^4I15/2 and the green emission of ^2H11/2/^4S3/2 in nanoparticles with lower concentration of Yb^3＋ result from a two-photon excitation, In nanocrystals with higher Yb^3＋ concentration, the red emissions from a two-photon excitation, while the green emissions from a three-photon excitation, The luminescence dynamics indicates that as the particle size decreases, both the rise and the decay time constants become shorter, As the size decreases to several nanometres, the rise process nearly disappears, suggesting that the upconversion luminescence originates mainly from self-excitation of Er^3＋, instead of the energy transfer of Yb^3＋→ Er^3＋.     

A novel strong green phosphor： K3Gd（PO4）2：Ce^3＋, Tb^3＋ for a UV-excited white light-emitting-diode

A series of K3Gd1-x-y（PO4）2：xCe^3＋, yTb^3＋ phosphors are synthesized by the solid-sate reaction method. X-ray diffraction and photoluminescence spectra are utilized to characterize the structures and luminescence properties of the as-synthesized phosphors. Co-doping of Ce^3＋ enhances the emission intensity of Tb^3＋ greatly through an efficient energy transfer process from Ce^3＋ to Tb^3＋. The energy transfer is confirmed by photoluminescence spectra and decay time curves analysis. The efficiency and mechanism of energy transfer are investigated carefully. Moreover, due to the non- concentration quenching property of K3Tb（PO4）2, the photoluminescence spectra of K3Tb1-x（PO4）2：xCe^3＋ are studied and the results show that when x = 0.11 the strongest Tb^3＋ green emission can be realized.     

Structural Change in Au^3＋-Doped BK7 Glass Irradiated by Femtosecond Laser

We report on structural change in an Au^3＋-doped BK7 glass irradiated by an infrared femtosecond laser at 800 nm. A grating structure is inscribed in the glass sample. The glass sample is then annealed at various temperatures. Structural change of the grating is observed by an optical microscope. Absorption spectra indicate that colour centres are induced after the laser irradiation, and they decrease with increasing annealing temperature. Au nanoparticles are precipitated at high temperatures （≥ 600℃）. The mechanisms of the phenomena are discussed.     

Effects of Yb^3＋ in Er^3＋/Yb^3＋ Codoped Fluorophosphate Glasses

For the Er^3＋ /Yb^3＋ codoped fluorophosphate glasses, Judd-Ofelt theory is used to analyse the influence of YbF3 as not a sensitizer but an average component on the spectroscopic properties around 1530nm emission. The double roles of Yb^3＋, as a sensitizer and as an average component, are discussed. It is found that Yb^3＋ as an average component contributes to the increase of fluorescence lifetime, and Yb^3＋ as a sensitizer has the best sensitization when its concentration is 2.4 mol%.     

An effective surface-enhanced Raman scattering template based on gold nanoparticle/silicon nanowire arrays

A large-scale Si nanowire array （SiNWA） is fabricated with gold （Au） nanoparticles by simple metal-assisted chemical etching and metal reduction processes. The three-dimensional nanostructured Au/SiNWA is evaluated as an active substrate for surface-enhanced Raman scattering （SERS）. The results show that the detection limit for rhodamine 6G is as low as 10-7 M, and the Raman enhancement factor is as large as 105 with a relative standard deviation of less than 25%. After the calibration of the Raman peak intensifies of rhodamine 6G and thiram, organic molecules could be quantitatively detected. These results indicate that Au/SiNWA is a promising SERS-active substrate for the detection of biomolecules present in low concentrations. Our findings are an important advance in SERS substrates to allow fast and quantitative detection of trace organic contaminants.     

Kr L X-ray and Au M X-ray emission for 1.5 MeV–3.9 MeV Kr~(13+) ions impacting on an Au target

Kr L X-ray and Au M X-ray emission for Kr13＋ ions with energies of 1.5 MeV and 3.9 MeV impacting on an Au target are investigated at heavy ion research facility in Lanzhou （HIRFL）. The L-shell X-ray yield per ion of Kr is measured as a function of incident energy. In addition, Kr L X-ray production cross section is extracted from the yield and compared with the result obtained from the classical binary-encounter approximation （BEA） model. Furthermore, the intensity ratio of the Au M/33 to Ma1 X-ray is investigated as a function of incident energy.     

多体系多波长计算光度法同时测定镧铈镨钕钐铕钆

本文以DBC-偶氮氯膦为显色剂,并且在显色体系中加入不同量的EDTA-Na2P2O7作为竞争配位剂,使得七组分轻稀土组分间吸收光谱灵敏度的差别逐渐加大,从而增加了轻稀土混合物体系组分间吸收光谱的线性独立性.利用数值稳定性较强的约束优化算法--可变容差法处理光谱数据,对不同浓度比例的七组分轻稀土混合物体系(La3+,Ce3+,Pr3+,Nd3+,S m3+,Eu3+,Gd3+)的测定,取得了较满意的结果.     

Photoacoustic Spectra of Sm3+, Eu3+, Dy3+ Complexes

The complexes crystals of Sm(Ac)3.4H₂O, Eu(Ac)3.4H₂O and a new complex Dy2(Ac)(NO3)4.12H₂O were synthesized and their PA spectra were determined firstly. All their PA spectra absorptions are interpreted. The fluorescence properties of Sm³⁺, Eu³⁺, Dy³⁺ and the relaxation process models were studied by their PA spectra.     

YLiF4: Er3+, Tm3+, Yb3+中Tm3+浓度对上转换发光的影响

利用水热法合成了YLiF4: Er3 , Tm3 , Yb3 , 其中Er3 和Yb3 的浓度保持固定不变, 分别为1 mol%和1.5 mol%, Tm3 浓度变化范围是2 mol%～8 mol%. 在这种共掺杂体系中, 同时观察到了Er3 , Tm3 和Yb3 的吸收, 且Tm3 的吸收随着其浓度的增强而增强. 在980 nm光的激发下, 当Tm3 浓度很小时, 这种材料的上转换发光为白光. 其中蓝光主要来源于Tm3 的激发态1G4到基态3H6的跃迁, 绿光来源于Er3 的4S3/2和2H11/2到基态4I15/2的跃迁, 红光既来源于Tm3 的1G4→3F4的跃迁, 也来源于Er3 的4F9/2→4I15/2的跃迁. 并且这种上转换发光强度随着Tm3 浓度的增强而降低, 但对应不同能级跃迁的发光强度降低的幅度不同, 这是因为Er3 和Tm3 之间的相互作用.     

ZBLAN玻璃中Nd~(3+),Tm~(3+),Yb~(3+)的上转换发光特性

采用高温固相法制备了Nd,Tm和Yb掺杂的ZBLAN玻璃上转换材料.Tm3+,Yb3+的摩尔浓度分别固定为0.01%,0.3%,Nd3+摩尔浓度变化范围为0.1%～2%.在室温下,测试了样品在300～1 000nm间的吸收光谱.在798 nm近红外光激发下,测试了样品的上转换光谱.实验发现,样品在798 nm红外光激发下发出了较强的多波段(红,蓝和绿)的可见光.由上转换可见光各波段的发射谱线,给出了能级跃迁机制.蓝光主要来源于Tm3+的激发态1G4到基态3H6的跃迁,绿光来源于Nd3+的2H7/2到基态4I9/2的跃迁,红光来源于Nd3+的2H11/2到基态4i9/2的跃迁.研究发现,在Nd3+,Tm3+,Yb3+:ZBLAN玻璃样品中存在激发态吸收,能最转移和交叉弛豫等上转换过程.其发光机理是Nd3+,TM3+和Yb3+离子之间的能量转移.根据Nd3+摩尔浓度不同其上转换发光强度不同,分析了掺入稀土的浓度对上转换发光效率的影响.当Nd3+浓度为1.5%(摩尔分数)时上转换发光最强,大于1.5%后发光开始减弱.     

计算光度法同时测定镧、铈、镨、钕

以二溴一氯-偶氮氯膦(DBC-CPA)为显色剂,并且在显色体系中加入不同量的EDTA-Na2P2O7作为竞争配位剂,使得4组分轻稀土组分间吸收光谱灵敏度的差别加大,从而增加了轻稀土混合物体系组分间吸收光谱的线性独立性,采用数值稳定性强的约束优化算法-可变容差法处理光谱数据,对不同深度比例的4组分轻烯土混合物体系(La^3 ,Ce^3 ,Pr^3 ,Nd^3 )的测定,取得了较为满意的结果.     

Lead fluorosilicate glass ceramics doped with Nd3+, Er3+, and Yb3+

Glasses in the PbF₂-PbO-SiO₂ system doped with 1 mol % of rare-earth elements (Nd³⁺, Er³⁺, or Yb³⁺) are synthesized and studied. The glasses were heat-treated in order to obtain glass ceramics with a fluoride crystalline phase. The changes in the structure and spectral optical properties of glass ceramics with respect to initial glasses were determined by using X-ray diffraction analysis and by studying the luminescent characteristics of dopant ions.     

EPR of Er3+, Nd3+, and Ce3+ ions in YAlO3 single crystals

EPR spectra of the Er³⁺, Nd³⁺, and Ce³⁺ ions substituting for the Y³⁺ ion in the YAlO₃ yttrium orthoaluminate lattice are studied. The EPR spectra of these rare-earth ions are described by a spin Hamiltonian of rhombic symmetry with an effective spin S=1/2. The principal values of the g tensors were determined from an analysis of the angular dependences of the EPR spectra. The orientation of the local magnetic axes of paramagnetic centers relative to the YAlO₃ crystallographic directions are shown to depend on the actual rare-earth species. The EPR spectra exhibit a hyperfine structure due to the ¹⁶⁷Er, ¹⁴³Nd, and ¹⁴⁵Nd odd isotopes, which permitted unambiguous identification of these spectra. The hyperfine coupling constants for the odd erbium and neodymium isotopes are determined.     

5d-4f luminescence of Nd3+, Gd3+, Er3+, Tm3+, and Ho3+ ions in crystals of alkaline earth fluorides

The vacuum ultraviolet emission spectra of alkaline-earth fluoride (CaF₂, SrF₂, BaF₂) crystals with rare earth impurity ions (Nd, Gd, Er, Tm, Ho) have been investigated. The main luminescence bands are described well by the transitions from the lowest excited 5d state to different 4f levels of rare earth ions.     

掺Ce3+、Gd3+、Tb3+的CaLaB7O13的光

采用固相反应法合成了接Ce3+、Gd3+、Tb3+的CaLaB7O13,并测定了它们的光谱。在Ce3+的光谱中发现文献中尚未报导的317nm激发峰和293nm发射峰。293发射属于不常见的5d能带中次最低能级向基态的跃迁,并随着Ce3+离子浓度增加而变弱,当掺杂浓度大于0.1mol时,293nm发射峰消失。