利用同步辐射进行X射线激发光学发光研究

本文介绍利用北京正负电子对撞机产生的同步辐射X光进行激发晶体(GGG:Nd~(3+),LaF_3:Nd~(3+))的光学发光研究的有关实验技术和设备。     

NdCl_3:Nd~(3+)的斯塔克子能级

首次测定了NdCl_3:Nd~(3+)的吸收光谱并根据光谱定出了它的斯塔克子能级,进一步用JuddRacah不可约张量方法作了理论计算。实验上,观察到NdCl_3:Nd~(3+)的子能级相对于LaCl_3:Nd~(3+)的子能级约有10—30cm~(-1)的移位。计算结果表明,移位的主要原因是由于在两种晶体中4f电子间的库仑作用有所不同。     

激光工作物质

TN244 2004031716 Nd~(3 ):Y_(0.5)Gd_(0.5)VO_4晶体生长和基本特性=Growth andbasic properties of Nd~(3 ):Y_(0.5) Gd_(0.5) VO_4 crystal[刊,中]/张连翰(中科院安徽光机所.安徽,合肥(230031)),杭寅…∥功能材料与器件学报.—2003,9(2).—143-146 Nd~(3 ):Y_(0.5)Gd_(0.5) VO_4晶体作为一种新的激光材料,可以用中频感应加热提拉法生长。X射线粉末衍射分析     

铬、钕双掺钆镓石榴石(Cr4+,Nd3+):Gd3 Ga5 O12激光晶体光学性能的研究

用提拉法生长了掺铬、钕的钆镓石榴石(Cr^4 ,Nd^3 ：GGG)自调Q激光品体。报道了室温下的吸收光谱和荧光光谱特性。分析了Cr离子浓度对光谱性质的影响。比较了Cr^4 ：GGG,Nd^3 ：GGG和(Cr^4 ,Nd^3 )：GGG晶体吸收光谱的关系。测量了(Cr^4 ,Nd^3 )：GGG晶体和Nd^3 ：GGG晶体的荧光寿命,它们分别是33μs和250μs。实验表明,(Cr^4 ,Nd^3 )：GGG晶体是一种非常有潜力的自调Q激光晶体,可以实现大功率激光器的小型化和全固态化。     

LiYF_4:Nd~(3+)的吸收光谱和它的子能级

生长了LiYF_4:Nd~(3+)单晶体,从吸收光谱测定了Nd~(3+)在LiYF_4中的斯塔克子能级的能量值,首次发现,在同种晶体中,由于相对应的晶轴长度的不同将使子能级的能量值稍有差异。同时,又根据Judd-Racah理论进行了计算。     

铬、钕双掺钆镓石榴石(Cr~(4+),Nd~(3+))∶Gd_3Ga_5O_(12)激光晶体光学性能的研究

用提拉法生长了掺铬、钕的钆镓石榴石(Cr4+,Nd3+∶GGG)自调Q激光晶体。报道了室温下的吸收光谱和荧光光谱特性。分析了Cr离子浓度对光谱性质的影响。比较了Cr4+∶GGG,Nd3+∶GGG和(Cr4+,Nd3+)∶GGG晶体吸收光谱的关系。测量了(Cr4+,Nd3+)∶GGG晶体和Nd3+∶GGG晶体的荧光寿命,它们分别是33μs和250μs。实验表明,(Cr4+,Nd3+)∶GGG晶体是一种非常有潜力的自调Q激光晶体,可以实现大功率激光器的小型化和全固态化。     

Nd:GGG晶体荧光寿命的测试

针对Nd:GGG激光器,介绍了荧光寿命测试原理,设计了低频窄脉宽荧光寿命测试系统.该系统由光源、光路系统、驱动电路和探测系统等几部分组成.利用脉冲取样技术测试了Nd:GGG晶体的荧光寿命约为250μs左右.     

YAlO_3:Nd~(3 )的吸收光谱

从0.33—5.7μm的波长范围内系统地测定了温度为10K、90K和30OK时YAlO_3:Nd~(3 )的吸收光谱,定出Nd~(3 )在晶体场作用下的斯塔克(Stark)子能级。并在10K到663K的温度范围内,观察了部分光谱线的温度效应,得到一些有意义的结果。     

平面镜反射率的标定及修正

 研究了用同步辐射源标定软X光掠入射平面镜的反射率。实验采用北京同步辐射装置(BSRF)-3W1B束线及反射率计靶室，在50~1 500 eV能区，做了C，Si，Ni和Au材料平面镜在1°~7°掠射角下的反射率标定曲线。由于3W1B束线的单色器采用变间距光栅作色散元件，光栅分光必然存在高次谐波，高次谐波严重影响光源的单色性，从而给平面镜的反射率标定值带来误差。前置滤片虽然能有效抵制高次谐波，但不能完全消除高次谐波。为此，利用透射光栅对光源做了单色性研究，给出高次谐波在不同能区所占光源强度的比例，从而对平面镜反射率标定值做出修正。     

BSRF光电子能谱仪光源尺寸要求研究及束线改进

不同的光电子能谱仪有不同的探测面积和接收角度,在所探测范围内实验光源的单位面积强度直接决定了实验计数率的高低, 因此了解所用能谱仪在什么样大小的光源尺寸下实验以获得最佳的实验条件就显得很为重要. 本文分析了北京同步辐射实验室光电子能谱仪在4B9B光束线所提供的光源下对能谱仪测试的实验结果,从现在所用的光源尺寸大小上讨论了以往实验计数及分辨能力不很理想的原因,提出了在现有能量分析器条件下4B9B光束线的光源尺寸要求.从而进一步确定了光束线的高能分支增加后聚焦镜以改善聚焦的改进方案,同时对束线的低能分支也作了相应的改进设计.     

Interconfigurational 5d?→?4f luminescence of Ce(3+) and Pr(3+) in Ca(9)Lu(PO(4))(7)

Ca(9)Lu(PO(4))(7):Ce (3+) and Ca (9)Lu (PO (4))(7):Pr (3+) polycrystalline materials were synthesized by solid state reaction at high temperature. The materials were characterized by powder x-ray diffraction (XRPD). The luminescence spectroscopy and the excited state dynamics of these compounds were investigated upon excitation with UV/VUV synchrotron radiation. Both materials showed efficient and fast 5d-4f emission upon direct VUV excitation into the 5d levels but only Ca(9)Lu(PO(4))(7):Ce (3+) revealed luminescence upon excitation across the bandgap. The decay kinetics of the 5d-4f emission upon VUV intra-center excitation is characterized by a decay time of 29?ns for Ce (3+) and 17 ns for Pr (3+) with no significant build-up after the excitation pulse. For the both compounds, no significant temperature dependence of the 5d-4f emission lifetime was observed within the range 8-300?K.     

Measurement of L subshell fluorescence yield ratios of some high Z elements by selective excitation method

The L₁, L₂ and L₃ subshells of Hf, Ta and Re atoms have been excited selectively by using microprobe XRF beam line, Indus‐2, RRCAT, India. The consequent characteristic L X‐ray photons, emitted from the targets due to creations of vacancies in L subshells, are measured using silicon drift detector (X‐123) spectrometer. As the energy of synchrotron radiation increases, the contribution of characteristic L X‐ray intensity increases. The advantage of the increase in the intensity of the characteristic L X‐ray photons with an increase in the energy of synchrotron radiation has been used to determine the L subshell fluorescence yield ratios of Hf, Ta and Re atoms by adopting the selective excitation method. The measured ratios of L subshell fluorescence yield have been compared with theoretical and other experimental values.     

钕离子浓度对受激发射截面的影响

 通过对N31型磷酸盐激光钕玻璃的6种钕离子浓度进行实验，采用Judd－Ofelt模型对样品进行分析，发现随着钕离子浓度的增加，受激发射截面逐渐减小。因此在激光系统设计中，应充分考虑钕离子浓度的影响。选择浓度合适的钕玻璃作为工作物质，可使激光系统性能达到最优。     

N_2(B~3Ⅱ_g)高振动态在Xe原子中的碰撞激发和弛豫

在用双光子激发产生的Xe(5p~56p)原子与N_2分子碰撞过程中,有效地生成了N_2(B~3П_g,v=9～14)振动激发态.观察到相应的Δv=4的N_2(B~3П_g-A~3∑_u~+)辐射跃迁萤光,测量了Xe(6p)原子在N_2中的淬灭速率常数,对碰撞弛豫过程进行了讨论.     

Resonant Auger decay in the L2,3-MM spectrum of Ar excited by electron bombardment

The L_2,3-MM Auger spectrum of argon was measured using electron beam excitation. A weak structure on the high energy side of the main transitions was identified as corresponding to the resonant Auger transitions by comparing these spectral structures with individual resonant Auger spectra excited by monochromatic synchrotron radiation.     

Confinement resonances in photoionization of Xe@C₆₀+

Experimental evidence is presented for confinement resonances associated with photoabsorption by a Xe atom in a C60 cage. The giant 4d resonance in photoionization of Xe is predicted to be redistributed into four components due to multipath interference of photoelectron waves reflected by the cage. The measurements were made in the photon energy range 60-150 eV by merging a beam of synchrotron radiation with a mass/charge selected Xe@C??+ ion beam. The phenomenon was observed in the Xe@C(58)(3+) product ion channel. [corrected]     

High power acceleration of an HSC type injector for cancer therapy

A hybrid single cavity(HSC) linac, which is formed by combining a radio frequency quadrupole(RFQ)and a drift tube(DT) structure into one interdigital-H(IH) cavity, is fabricated and assembled as a proof of principle injector for cancer therapy synchrotron, based on the culmination of several years of research. The HSC linac adopts a direct plasma injection scheme(DPIS), which can inject a high intensity heavy ion beam produced by a laser ion source(LIS). The input beam current of the HSC is designed to be 20 m A C~(6+) ions. According to numerical simulations, the HSC linac can accelerate a 6-m AC~(6+) beam, which meets the requirement of the needed particle number for cancer therapy(108-9ions/pulse). The HSC injector with the DPIS method makes the existing multiturn injection system and stripping system unnecessary, and can also bring down the size of the beam pipe in existing synchrotron magnets, which could reduce the whole cost of synchrotron. The radio frequency(rf) measurements show excellent rf properties for the resonator, with a measured Q equal to 91% of the simulated value. AC~(6+) ion beam extracted from the LIS was used for the HSC commissioning. In beam testing, we found the measured beam parameters agreed with simulations. More details of the measurements and the results of the high power test are reported in this paper.     

基于多层膜偏振元件的同步辐射光束线偏振特性测量研究

利用自行研制的同步辐射软X射线多层膜综合偏振测量装置, 对北京同步辐射装置(BSRF)的3W1B软X射线光束线的偏振特性进行了系统的研究. 给出了多层膜偏振元件起偏前后的测量结果, 测量能量为206eV时, 经反射镜、光栅等光束线光学元件后输出的线偏振度(起偏前)为0.585, 经多层膜偏振元件起偏后输出光的 线偏振度达到0.995.