钡铝酸盐绿荧光粉化学组成对光谱特性的影响

采用固相合成法制备了钡铝酸盐绿色荧光粉xBaO·6Al2O3∶Mnz,研究了化学组成对晶体结构、VUV发光性能的影响。当0.7≤x≤1.5,随着Ba2+的增加存在BaAl13.2O20.8→BaAl12O19→BaAl9.2O14.8的基质结构转化。Ba2+含量较低时,存在与基质晶格共晶的BaMnAl10O17结构,并且随着Mn2+含量的增加BaMnAl10O17结构的数量增加。Ba2+含量对VUV激发光谱谱形有较大影响;Mn2+含量增加使发射光谱略有增宽。当Ba2+、Mn2+的含量分别为x=1.0与z=0.10～0.12时,具有最优的发光效率。     

Temperature Effects on the Vacuum-UV (VUV)-Initiated Oxidation and Mineralization of Organic Compounds in Aqueous Solution Using a Xenon Excimer Flow-through Photoreactor at 172 nm

The 172 nm irradiation of aqueous solutions of organic compounds with a xenon excimer (Xe₂?) flow-through photoreactor leads to the oxidation and mineralization of the organic content of the water. In view of potential technical applications, it is of fundamental interest to investigate temperature effects on the efficacy of these processes. Therefore, water samples containing Rhodamin B (RhB) or methanol as model substrates were vacuum-UV (VUV) irradiated under controlled thermal conditions. The pseudo–first-order bleaching kinetics of RhB solutions and the pseudo–zero-order reaction kinetics of oxidation and mineralization of aqueous methanol solutions were quantitatively established by UV/Vis spectrophotometry, by measurement of the methanol concentration using capillary gas chromatography and the total organic carbon (TOC) content of the solutions, respectively. In the water temperature range from 20 to 50°C no significant effects on the pseudo–first-order rate constant of RhB bleaching (k_RhB) and the pseudo–zero-order rate constants of methanol oxidation (k_MeOH) and TOC diminution (k_TOC) were observed with our particular flow-through photoreactor system using a Xe₂? excilamp.     

Vacuum UV photo-oxidation of polystyrene

Polystyrene (PS) was treated with vacuum UV (VUV) (λ = 104.8 and 106.7 nm) photo-oxidation and X-ray photoelectron spectroscopy detected a controlled increase in the atomic percentage of oxygen up to a saturation level of ca. 20 at% O. Initially, C–O and carbonyl groups are observed due to the formation of alcohols, ethers, esters, and ketones. Water contact angle measurements showed ca. 25% increase in hydrophilicity of the surface with oxidation. Atomic Force Microscopy observed little changes in surface roughness with treatment time. The super water absorbent polymer poly(acrylic acid) was thinly grafted to the modified PS surface.     

Plasma treatment and adhesion properties of a rubber-modified polypropylene

In this study, cold, glow-discharge plasmas were used as a pretreatment method for the lacquering of rubber-modified polypropylene plates. This type of material is also referred to as thermoplastic polyolefins (TPOs). The effects of plasma treatments at radio- and microwave frequencies (RF and MW) and in combined MW-RF modes were studied, as were the effects of plasma power-to-gas flow (P/F) ratios and of discharges in oxygen, nitrogen, air, argon, and hydrogen. Surface characterization was carried out by contact angle measurements with water as the wetting liquid, and by XPS analyses. The adhesion between a two-component polyurethane (PUR) lacquer and plasma-treated TPO plates was evaluated by 180°-peel testing. The wettability of TPO surfaces was not affected by the plasma frequency or the P/F ratio, while the influence of the discharge gas was noticeable. Furthermore, no correlation between wettability and peel force could be found. Instead, lacquer adhesion was shown to be highly dependent on the P/F ratio and on the choice of discharge gas. The peel forces were found to be in the range of 0.1-35 N/15 mm, and the locus of failures was shown (by visual inspection or by XPS analysis) invariably to be in the TPO substrate. Electromagnetic radiation, most likely vacuum-ultraviolet (VUV) emission (<200 nm), was proposed to be a critical factor in plasma treatments. Attributed to VUV radiation was the creation of radicals in the TPO substrate; these lead to severe chain scission reactions and thereby govern the cohesive strength of the near-surface region of the substrate.     

Photocatalysis of p-chlorobenzoic acid in aqueous solution under irradiation of 254 nm and 185 nm UV light

The photolytic and photocatalytic degradation of p-chlorobenzoic acid (p-CBA) in aqueous solution were investigated using two kinds of low-pressure mercury lamps: one emitted at 254 nm and the other emitted at 254 nm and 185 nm. Both the photolytic and photocatalytic degradations of p-CBA followed pseudo first-order reaction rate form. The rate constants decreased with increase of initial concentration in VUV and TiO2/VUV. The TiO2/VUV was the most efficient process, in which rate constants was 3.0-6.5 times as that in TiO2/UV depending on the initial concentration. The gas bubbling efficiently improved the mass transfer and the kind of bubbling gas had evident influence on the reaction rate except in UV photolysis. TOC reduction rate was greatly reduced in VUV and TiO2/VUV processes when bubbled with nitrogen gas, it was no more than one third of that when bubbled with oxygen, however, the degradation rate of p-CBA was not affected by bubbled nitrogen so greatly.     

反斯托克斯拉曼转换增益系数的最佳化

研究了反斯托克斯拉曼转换与受激拉曼散射之间的竞争过程，讨论了反斯托克斯拉曼转换增益系数的最佳化。     

Influence of He‐Ne‐Xe gas composition on vacuum ultraviolet ray spectra in plasma‐display panels

The vacuum ultraviolet (VUV) ray emission characteristics for plasma‐display panels (PDPs) were studied with respect to various three‐component (He‐Ne‐Xe) and two‐component (He‐Xe and Ne‐Xe) gas systems. In the 4% Xe‐25% Ne‐He balance and 4% Xe‐He balance, an increase in the pressure contributed to an increase in the 147‐nm atomic emission, and above a certain point this decreased, while in the 4% Xe‐Ne balance it was saturated. The 172‐nm dimer emission showed a nearly linear increasing behavior with pressure and Xe content irrespective of its composition. In the various Xe with 25% Ne‐He balance gases, it was shown that total integrated VUV intensity can directly represent the luminance of real panels with the same gas compositions. Xe‐content variation showed similar characteristics of VUV emission as pressure variation both in two‐component (various Xe‐Ne balance) and three‐component (various Xe‐25% Ne‐He balance) systems. Therefore, different compositions with the same Xe partial pressure showed nearly the same optical properties. For the case of Ne content variation with 4% Xe, the 147‐nm peak increased and the 172‐nm peak decreased to 85% Ne, but above this point both intensities decreased.     

The effect of misalignment errors in optical elements of VUV polarimeter

We have designed a Vacuum Ultra Violet polarimeter for Indian Synchrotron Radiation Source Indus-1. This polarimeter will be installed on a toroidal grating monochromator-based beamline. Polarimeter consists of four-mirror phase retarder and three-mirror linear polarizer. Three-mirror linear polarizer has glancing angles of incidence 23°, 46° and 23°, working in 200–1100 Å wavelength region, with linear polarizence greater than 90%. Detailed ray-tracing analysis was carried out to find the effect of various misalignment errors in each of the optical element of the polarimeter. It is found that misalignment errors in optical element of the polarimeter affect only the beam spot position and do not affect the spot size, polarization state and photon flux of outgoing beam, substantially. Accuracies in the linear and angular positions of optical elements in phase retarder and linear polarizer must be very precise to perform ellipsometric experiments. Tolerance limit for various misalignment errors has been obtained. Required accuracy in angular position around X-axis is more than that required in angular position around Z-axis.     

Luminescence of Eu^3 ＋ in LnAlO3 （Ln = Gd, Y） under UV and VUV Excitation

Single phases of LnAlO3 : Eu^3 ( Ln = Gd, Y ) were obtained by the process of evaporation of their nitric acid solution, and then pyrolysis of their nitrate salts. On monitoring by 613 nm emission, broad bands at around 270 and 170nm were observed in the excitation spectrum of Gd0.95Eu0.05AlO3. These peaks could be assigned to charge transfer (CT)transitions of Eu^3 -O^2- and Gd^3 -O^2- respectively. All the transitions observed in Gd0.95Eu0.05AlO3 are faithfully reproduced in the Y0.95Eu0.05AlO3, but with an exception of the ^8S7/2→^6I11/2 transition of Gd^3 . The 153 nm broad band could be the CT transition of Y^3 -O^2 - . Accordingly, the efficiency luminescence of (Gd, Y) BO3 : Eu^3 was explained as a result of CT transitions of Gd^3 -O^2- and Y^3 -O^2- under 147 nm excitation. Under VUV excitation, Gd0.95Eu0.05AlO3 exhibits a bright red luminescence with CIE chromaticity coordinates of (0.623, 0. 335) with a PL intensity of 30 of the commercial phosphor (Gd, Y) BO3 : Eu^3 (KX-504A). The PL spectrum of Y0.95Eu0.05AlO3 is similar to that of Gd0.95Eu0.05AlO3. Calculation of the color coordinates gives x = 0. 636, y = 0. 340 with a PL intensity of 50 of the (Gd, Y) BO3 : Eu^3 ( KX-504A) for Y0.95Eu0.05AlO3, and confirms that it has the appearance of pure spectral red, corresponding approximately to 608 nm. It can be concluded that LnAlO3:Eu^3 is a promising red VUV phosphor.     

Spectroscopy of Pr^3＋4f5d Configuration in LaF3 Nanocrystals／Oxyfluoride Glass Ceramics

Theinterestofinvestigatingthe 4fn -15delectronicconfigurationofthetrivalentrareearth (RE)ionsisbasedonavarietyofapplicationsinthevacuumultra violet (VUV)regionofthespectrum ,suchasthede velopmentofplasmadisplaypanelsandmercury freefluorescenttubes[1] .Amo…