Infrared spectra and structural properties of Na2O-B2O9-ZrO2-SiO2 glasses

The structure of glasses of the Na₂O-B₂O₃-ZrO₂-SiO₂ system, which form the basic ingredients of opacified zirconium-type glazes, was studied by infrared spectroscopy. The problems of boron ion coordination and the role of Zr⁴⁺ in glass structure are considered.The present paper is a continuation of [1], which deals with glasses of the Na₂O-B₂O₃-ZrO₂-SiO₂ system.     

有机-无机复合ZrO2-SiO2平面光波导

采用溶胶-凝胶法合成ZrO2-SiO2有机一无机复合光波导材料,通过改变其中ZrO2的含量来调节材料的折射率,使材料分别适用于平面光波导的导光层(ng≈1．497)和衬底层、包层(mb=nc≈1．479)。采用旋转涂膜工艺和相应的热处理,在单晶硅基片上制备衬底层、导光层和包层等薄膜,其中导光层介质因具有感光性而可通过紫外光刻来制备光路图案。所得有机一无机复合ZrO2-SiO2板型平面光波导(衬底层 导光层),用棱镜耦合截断法测试其光损耗在632．8nm波长处约为0．8dB／cm。对板型平面波导的导光层薄膜进行紫外光刻和异丙醇淋洗,制备出脊状光波导通道,在覆盖包层后,即获得埋层沟道式平面光波导。采用端耦合截断法测试了埋层沟道式平面光波导的光损耗(小于0．1dB／cm),并观察了其近场图像以及导光材料在近红外窗口的吸收光谱。     

Methyl orange adsorption by microporous and mesoporous TiO2-SiO2 and TiO2-SiO2-Al2O3 composite xerogels

We investigate the adsorption behavior of methyl orange (MO) on composite xerogels. Mesoporous TiO₂-SiO₂ and TiO₂-SiO₂-Al₂O₃ xerogels are prepared by hydrolysis of tetraethyl orthosilicate (TEOS), tetrabutyl orthotitanate (TBOT), and AlCl₃ ·6H₂O using HCl as a catalyst and cetyltrimethylammonium bromide (CTAB) as a templating agent. The corresponding microporous xerogels are also prepared without addition of CTAB. These xerogels are then characterized by XRD, FTIR, and BET.We find that MO is adsorbed by the mesoporous xerogels in acidic solutions, showing Langmuir type adsorption isotherms. We also find that the adsorption decreases with increasing temperature. It is suggested that adsorption exhibits a sieve effect and that MO is adsorbed through electrostatic attraction and hydrogen bonding between MO and the xerogels.     

Photoabsorption resonances of Na20, Na21Cl and Na22Cl2 clusters

Plasma resonance profiles in the visible part of the spectrum were measured by photoabsorption spectroscopy for the clusters Na₂₀, Na₂₁Cl and Na₂₂Cl₂ in a beam. The resonance positions in Na₂₀ and Na₂₁Cl are close, suggesting that the Cl^- ion does not locate at the center of the metallic droplet and does not strongly modify the effective valence electron density. The spectrum of Na₂₂Cl₂ is noticeably dissimilar to the other two, raising the possibility of structural differences and/or incomplete charge transfer.     

Infrared absorption spectra and structure of TiO2-SiO2 composites

The composites xTiO₂-(1−x)SiO₂ (x = 0.1, 0.5, 0.9) were obtained by coprecipitation from solutions of alkoxides: tetraethoxysilane (TEOS) and titanium tetraisopropoxide (TIPT). Intermolecular interaction of the components of the composite is apparent in the IR absorption spectra in the 928–952 cm⁻¹ region, and is connected with bending vibrations of the Si-O-Ti bond. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 75, No. 5, pp. 724–728, September–October, 2008.     

采用HfO2/SiO2溶胶-凝胶薄膜制备衍射光栅

采用溶胶-凝胶方法制备了具有光敏性的HfO2/SiO2溶胶-凝胶薄膜,并利用其光敏性制备了衍射光栅.采用XPS分析了薄膜的成份,证实了Hf元素的存在.并用椭偏仪测试了薄膜的折射率,结果证实了HfO2的加入确实提高了体系的折射率.利用其光敏性,采用X射线作曝光光源通过掩模进行曝光,利用曝光部分与未曝光部分的溶解度差,在薄膜上制备了高为0.8 μm、周期为1 μm的衍射光栅.     

20 Ne(34 Ne)原子与18 Na2(23 Na2,37 Na2)分子低温下冷碰撞的同位素效应研究

本文用多体刚性椭球模型计算了相对入射能量为190 meV时,氖的同位素原子²⁰Ne,³⁴Ne与钠的同位素分子¹⁸Na₂,²³Na₂,³⁷Na₂ 替代碰撞体系的态态转动激发积分散射截面和总转动激发积分散射截面,在此基础上计算并分析了相互作用势的不同区域对²⁰Ne-¹⁸Na_{2关键词： 多体刚性椭球模型 转动激发积分散射截面 钠同位素分子 椭球等势面}     

Room-temperature diode-pumped Yb, Na: PbF2 laser

Growth, spectroscopic properties, and laser performance of Yb, Na:PbF(2) crystals have been investigated. With a 2 mol.% Yb(3+)-doped sample we obtained 2.65 W output power at 1045 nm for 7.5 W of incident power at 976 nm. The laser wavelength could be tuned from 1017 to 1078 nm, showing the great potential of Yb, Na:PbF(2) as an amplifier medium for femtosecond pulses.     

Quantum dynamics of ultracold Na+ Na2 collisions

Ultracold collisions between spin-polarized Na atoms and vibrationally excited Na2 molecules are investigated theoretically, using a reactive scattering formalism (including atom exchange). Calculations are carried out on both pairwise additive and nonadditive potential energy surfaces for the quartet electronic state. The Wigner threshold laws are followed for energies below 10(-5) K. Vibrational relaxation processes dominate elastic processes for temperatures below 10(-3)-10(-4) K. For temperatures below 10(-5) K, the rate coefficients for vibrational relaxation (v=1-->0) are 4.8x10(-11) and 5.2x10(-10) cm(3) s(-1) for the additive and nonadditive potentials, respectively. The large difference emphasizes the importance of using accurate potential energy surfaces for such calculations.     

GeO2-SiO2纳米复合材料的合成及其光学特性研究

运用溶胶-凝胶法合成了GeO2-SiO2纳米复合材料,探索了为pH在2的条件下通过水解Si(OC2H5)4和GeCl4合成GeO2-SiO2干胶的过程.在100～1 200℃下对干胶进行热处理.采用UV光谱法测定了材料的光学性质,观察到随热处理温度的升高,样品光谱的吸收边向长波方向移动.由于温度的影响,晶粒长大,带隙能量减小,纳米微晶的量子尺寸效应显示出来.经X射线衍射分析,观察到了随热处理温度的增高,材料结构从无序到有序的转变过程,直到1 100℃时,有明显的微晶生成,其尺寸为5～10nm.     

Heat capacity of oxides in the Bi2O3-SiO2 system

The high-temperature heat capacity of Bi₄Si₃O₁₂, Bi₂SiO₅, and Bi₁₂SiO₂₀ has been investigated. It has been found that there is a correlation between the specific heat C _p ⁰ (298 K) and the composition of oxides in the Bi₂O₃-SiO₂ system.     

非晶纳米发光材料(Y,Eu)2O3-SiO2发射光谱的分析研究

EXAFS测定表明sol-gel方法制备的纳米非晶(Y,Eu)₂O₃-SiO₂发光材料中,发光中心Eu³⁺的局域环境和晶态X₂型Y₂SiO₅Eu中Eu³⁺离子的局域环境相似。以此结构为依据,用M. F. Reid的方案计算了晶场迭加模型中的能级参数及光谱强度参数,并得到了与实验结果基本一致的理论光谱图.