极紫外望远镜各通道夹角的测量

极紫外望远镜是由四个单通道的望远镜捆绑在一起,以便同时对太阳的相同部分观测,由于受地面装调以及发射过程中的影响,无法保证四个通道光轴严格平行,必然带来观测位置上的误差。只要测出各通道之间的光轴夹角,便可在像面上采取适当的处理方法,以便减小这种误差,但这一夹角的测量精度必须控制在0.1″内。为达到如此高的精度,采用了太阳局部边缘探测的方法,很好地解决了这一问题。     

具有新光学性质的Zn-Zn2SiO4纳米同轴线阵列

采用气相沉积技术在Si衬底上生长了Zn-Zn₂SiO₄芯-壳结构纳米同轴线阵列。根部呈笋状的纳米同轴线,直径约100nm,长度可以超过10μm;同轴线芯直径约50nm、壳层厚约25nm。通过X射线衍射的表征以及能量色散谱的线扫描,确定纳米同轴线的芯为Zn,壳层为Zn₂SiO₄。我们提出了一种新的生长机制,同时也为生长均匀的纳米同轴线提供一种新的技术。观察阴极荧光谱发现,纳米同轴线有三个主要发光带:强度最大的中紫外300nm发光、较弱的可见光区560nm以及红外谱区865nm的发光。对纳米同轴线截面的300nm发光峰观测发现,中紫外发光来源于Zn₂SiO₄壳层。正是这种同轴线的结构,使得其具备特殊的光学性质。     

A double-beam UV-laser differential absorption method for monitoring tropospheric trace gases

A method is described which uses the differential absorption of a narrow-band tunable ultra-violet laser for integrated measurements of tropospheric trace gas concentrations over a path length of 12.8 km, at near ground level. A XeCl excimer laser serves as a reference beam to compensate for turbulence-induced intensity losses. After suitable statistical averaging the method is capable of detecting differential absorptions as low as 10^-4, enabling the simultaneous detection of SO₂, CH₂O and of OH radicals around 308 nm.     

Scanning laser video camera/ microscope

A laser scanning system capable of scanning at standard video rate has been developed. The scanning mirrors, circuit design and system performance, as well as its applications to video cameras and ultra-violet microscopes, are discussed.     

锌(Ⅱ)对于甲基百里酚蓝与牛血清白蛋白相互作用的影响

采用荧光光谱、紫外-可见光谱研究了有/无金属Zn2+存在下甲基百里酚蓝(MTB)与牛血清白蛋白(BSA)的相互作用.实验结果表明,无论Zn2+离子存在与否,MTB与BSA之间均为一形成复合物的静态猝灭过程.根据Stern-Volmer方程和Lineweaver-Burk方程求出了其结合常数与热力学参数,发现Zn2+离子存在时,MTB与BSA间的作用力由静电力转为氢键和Van der Waals力作用为主,认为金属Zn2+以"离子架桥"的方式参与MTB与BSA的结合过程,从而ΔH对ΔG的贡献增大.     

基于非色散紫外算法的一氧化氮气体检测与分析

提出了一种基于非色散紫外(NDUV)算法,利用光电二极管阵列(PDA)探测器和光谱仪检测一氧化氮气体的分析方法。通过对比分析不同积分次数下一氧化氮吸收谱和无吸收谱内不同波长宽度的总光强,引入光源影响因子F和吸收谱因子B,得到吸光度与浓度的拟合方程及相关系数。结果表明,采用合适的拟合阶数、拟合波长宽度和分析方法,吸光度与浓度的二阶拟合相关系数可达0.999 9以上, 通过拟合方程所获得的待测气体浓度与标准值浓度的误差在3%以内。     

Pentacyclic Triterpenoids,Phytosteroids and Fatty Acid Isolated from the Stem-bark of Cola lateritia K. Schum. (Sterculiaceae) of Cameroon origin; Evaluation of Their Antibacterial Activity

The phytochemical investigation on the chemical constituents of dichloromethane-methanol (1:1) stem-bark extract of Cola lateritia K. Schum. (Sterculiaceae) led to the isolation and characterization of five pentacyclic triterpenoids, one fatty acid and two phytosteroids. The compounds were identified as heptadecanoic acid (1), maslinic acid (2), betulinic acid (3), lupenone (4), lupeol (5), friedelin (6), β-stigmasterol (7) and ß-sitosterol-3-O-ß-D-glucoside (8). Their structures were determined by NMR analysis (¹H, ¹³C, DEPT-135, COSY, HMBC and HSQC), high-resolution mass spectrometry (HR-ESI-MS) and comparisons with published data in the literature. This work, to the best of our knowledge, is the first isolation and identification of these compounds in pure forms from Cola lateritia. Also, compounds 1–3 are reported for the first time from Cola genus. In vitro antibacterial activity of the isolated compounds (1–8) and the crude extract were evaluated against Bacillus subtilis, Staphylococcus epidermidis, Enterococcus faecalis, Mycobacterium smegmatis, Staphylococcus aureus, Enterobacter cloacae, Klebsiella oxytoca, Proteus vulgaris, Klebsiella pneumonia, Escherichia coli, Proteus mirabilis and Klebsiella aerogenes with streptomycin, nalidixic acid and ampicillin as standard antibacterial drugs. Compound 2 was active against E. faecalis (MIC = 18.5 µg/mL), and it was 6.9 and 28 times lower and active than that of streptomycin (MIC 128 µg/mL) and nalidixic acid (MIC > 512 µg/mL) respectively. All the isolated compounds and crude extract showed significant activities against the tested bacterial strains.     

Ge掺杂β-Ga2O3晶体的发光性能研究

采用浮区法(FZ)生长Ge掺杂β-Ga2O3晶体,利用XRD和Raman光谱研究了掺杂对晶体结构的影响.透射光谱测试表明,随着Ge离子掺杂浓度增加,Ge∶ β-Ga2O3晶体光学带隙增大.在4.67 eV紫外光激发下,Ge∶ β-Ga2O3晶体的发光强度与β-Ga2O3晶体相当,发光衰减时间比β-Ga2O3晶体更快.     

Photophysical properties of highly efficient red-emitting CaTiO3:Eu phosphors under near ultra-violet excitation

The photophysical properties of europium-doped calcium titanate for near ultra-violet excitation were studied in order to investigate whether it is applicable to white light-emitting diodes. CaTiO₃:Eu³⁺ phosphors were synthesized by using the solid-state reaction method. The structures and basic properties of the phosphors were characterized by using X-ray diffractometer, scanning electron microscope, UV-visible spectrophotometer, and X-ray photoelectron spectrometer. The photophysical properties were examined by taking excitation and emission spectra. A strong red luminescence corresponding to ⁵D₀ → ⁷F₂ transition of Eu³⁺ under near ultra-violet excitation was observed. It was found that CaTiO₃:Eu³⁺ was a red-emitting phosphor and had higher efficiency for operation under near ultra-violet excitation.     

LiBaF3:Eu2+真空紫外光谱研究

在室温下，二价稀土离了 杂的LiBaF3:Eu^2 粉末样品中，Eu^2 的发射呈现双峰结构，有一峰值波长约为410nm的宽峰，对应于Eu^2 的5d-4f跃迁，以及另一峰值波长约为360nm的窄峰，对应于Eu^2 的4f-4f跃迁。在50－400nm波长范围，测量了样品的反射光谱，并利用Kramers-Kroenig关系，计算了吸收光谱。从吸收光谱中，可以看到在102nm处有明显的吸收边，得到LiBaF3材料的禁带宽度Eg约为12.1eV。在高能端有53.4,59.4,65.3,69.2和76.5nm的吸收峰，它们对应于Ba^2 的5p电子和F的2p电子芯能级之间的跃迁，在低能量的183.4nm处，有很明显的吸收峰，推测这对应于本征缺陷的吸收。更低能量的吸收峰，则对应于禁带中的一些杂质能级，在未经紫外光或X射线辐照之前，用长波长（＞450nm）光激发LiBaF3:Eu^2 粉末样品，可以观测到Eu^2 离子的360nm和410m发光，亦表现出光激励发光特性。