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151.
This paper considers the possibility of using tris--diketonate complexes of europium in polymethylmettacrylate as luminescent UV radiation converters for widening the range of spectral sensitivity of photodetectors (including TV ones). The absolute quantum yields of luminescence have been determined. Converters for the 220–380-nm range providing a quantum efficiency of the silicon photodiode and the CCD matrix in the UV range up to 40% of the efficiency at the maximum of the spectral characteristic have been devised. 相似文献
152.
设计了一套适用于加速器细长管道真空室的低温溅射镀TiN薄膜装置。利用该装置,对86 mm×2 000 mm的不锈钢管道真空室进行溅射镀TiN膜实验,并对镀膜实验结果进行分析,得到了适用于加速器管道真空室内壁溅射镀TiN膜的表面处理参数。样品测试结果表明:在压强为80~90 Pa、基体温度为160~180 ℃的镀膜参数下,不锈钢管道内壁获得的TiN薄膜最佳,薄膜沉积速率为0.145 nm/s。镀膜后真空室的二次电子产额明显降低。 相似文献
153.
报道了在兰州重离子加速器国家实验室电子回旋共振离子源原子物理实验平台上,用高电荷态40Arq+(1≤q≤12)离子作用于半导体Si固体表面时的电子发射产额实验测量.实验中,通过改变炮弹离子的电荷态和引出电压选取其不同的势能和动能,系统地研究了入射离子势能沉积和与其在固体中的电子能损对表面电子发射产额的贡献.结果表明,作为引起表面电子发射的两个主要因素,单离子的电子发射产额与炮弹离子在固体表面的势能沉积和电子能损都有近似的正比关系. 相似文献
154.
成功研制了测量绝缘体二次电子发射系数的测量装置,该装置主要由栅控电子枪系统、真空系统和电子采集系统组成,测量装置产生的原电子流的能量范围为0.8~60 keV。采用单脉冲电子枪法,测量了原电子能量范围为0.8~45 keV的多晶MgO的二次电子发射系数。测量中,收集极(偏置盒)离材料表面设置为约35 mm,偏置电压设置为 45 V。测量得到:用磁控溅射法制备的MgO的二次电子发射系数最大值约为2.83,处于 2~26范围内,其对应的原电子能量约为980 eV。这表明该装置测量的绝缘体二次电子发射系数是可信的,但用磁控溅射法制备的MgO的二次电子发射系数较低,这可能是制备MgO时引入了过多的杂质在MgO二次电子发射体里面所引起的。 相似文献
155.
Amol Sasane 《Journal of Mathematical Analysis and Applications》2010,370(2):703-715
We prove an abstract Nyquist criterion in a general set up. As applications, we recover various versions of the Nyquist criterion, some of which are new. 相似文献
156.
Joana Lia Ferreira Maria João Melo Ana Maria Ramos 《Polymer Degradation and Stability》2010,95(4):453-461
The photochemistry of poly(vinyl acetate), PVAc, homopolymer, of PVAc mixtures with selected pigments and fillers, and of accurate historic reproductions based on the colours prepared by Portuguese artist Joaquim Rodrigo and on those supplied by the company A Favrel was studied. The systems, applied as films, were irradiated at λ ≥ 300 nm and the changes followed by size exclusion chromatography, infrared spectroscopy, and colorimetry.PVAc as homopolymer or as an emulsion paint proved to be very stable to light, and after 5000 h of irradiation no gel fraction was observed. ΦR (λirr = 313 nm) for chain scission for PVAc was determined to be 7 × 10−8. This value indicates that the mechanism/s operating when irradiating at λ ≥ 300 nm are different from those previously published with irradiation involving 254 nm. No side-group scission was observed, and main chain scission is the foremost photodegradation mechanism. Also, the metal ions present in the pigments do not affect the photochemical stability of the polymer. 相似文献
157.
Xianping Qiu Huipeng Zhou Xiaofei Zhang Tinghua Xu Xingliang Liu Yingying Zhao 《Tetrahedron letters》2008,49(52):7446-7449
Two porphyrins with oligo-phenothiazine arms have been synthesized by a combination of Heck and Adler reaction, and their photophysical properties have been investigated by absorption and steady-state fluorescence spectroscopy. It is found that the excitation energy transfer occurs from the phenothiazine units to the porphyrin core, and that the porphyrins can emit intense red light with high fluorescent quantum yields. 相似文献
158.
L. T. Ashchepkov 《Computational Mathematics and Mathematical Physics》2008,48(4):531-538
Criteria for symmetry and boundedness are found for the combined solution set of a system of linear algebraic equations with interval coefficients. It is shown that the problem of the best inner interval estimation of a symmetric solution set can be exactly solved by linear programming methods. 相似文献
159.
L. Desgranges B. Pasquet S. Portier C.T.Walker D. Gavillet L. Raimbault 《Applied Surface Science》2008,255(4):863-865
The secondary ion energy spectrum of uranium depends on the experimental conditions, which is a problem for the application of a relative sensitivity factor (RSF) procedure for the measurement of the Nd concentration in UO2. This is interpreted as due to the dependence of the sputtering and ionisation yields of uranium on the oxidation state of the surface. Three experimental procedures are being tested to cope with this difficulty. 相似文献
160.
The truncated singular value decomposition is a popular method for the solution of linear ill-posed problems. The method requires the choice of a truncation index, which affects the quality of the computed approximate solution. This paper proposes that an L-curve, which is determined by how well the given data (right-hand side) can be approximated by a linear combination of the first (few) left singular vectors (or functions), be used as an aid for determining the truncation index. 相似文献