Photon statistics measurement for coherent fields

An efficient scheme for photon statistics measurement is presented based on the Hanbury-Brown-Twiss configuration. We set the sampling time Ts to satisfy the relationship of Ts 〈 Td 〈 Tm, where Td is the dead time of each detector and Tm is the laser pulse repetition period. And each single photon detector cannot detect more than one photon in each pulse. The approach can sufficiently eliminate the influences of the detector＇s dead time on photon statistics. At last, the photon statistics of coherent field is experimentally determined.     

Appropriate Gate Time for Single Molecular Photon Detection Based on Optimal Signal-to-Noise Ratio Analyses

Signal-to-noise ratio of fluorescence detection from a single molecule ＆ analysed by using time-gated techniques. It is found that the optimal signal-to-noise ratio can be obtained by choosing an appropriate gate time with a certain optical background. The dependences of molecular fluorescence lifetime and the optimal signal-to-noise ratio on the appropriate gate time are respectively discussed with two kinds of background sources~ chaotic state with uniform distribution and coherent state with exponential distribution in time domain. For chaotic state background we find that a certain range for appropriate gate time can be obtained with a definite fluorescence lifetime, larger fluorescence lifetime would lower the value of optimal signal-to-noise ratios. For coherent state background we find that there is also a narrow range of appropriate gate time when lifetime of single molecule is less than that of background photons.     

二-(2-乙基己基)磷酸在不同稀释剂中对钼(VI)的萃取

考察了Mo(VI)在盐酸水相与-二(2-乙基己基)磷酸的不同稀释有机相间的分配平衡,观察到萃取平稀常数按正辛烷、四氯化碳、苯、氯信、1,2-二氯乙烷、甲苯、甲基异丁基酮的次序递减,萃合物的组成也按这一顺序呈现规律性变化.文中将这些结果与稀释剂性进行了关联,得到萃取平衡常数与稀释剂的极性参数E~T间良好的线性关系.此外,本文还提出了H~2MoO~4的酸、碱式解离常数分别为0.158和1.21×10^13.     

稀土添加剂对超细ZrO2织构、结构的影响

Pure zirconia and zirconia containing Y or Ce were prepared by Supercritical Drying Method (SCD) followed by calcination in air at temperature up to 700℃. It was found that the zirconia containing Y or Ce possessed much higher specific surface area and larger pore volume than that of pure zirconia. The BET surface area of 3.4Y2O3-96.6ZrO2 without calcination and that calcined at 700℃ were 376.2 m2﹒g-1 and 80.0 m2﹒g-1 respectively, while the corresponding values of pure zirconia were 248.0 m2 ﹒g-1 and 47.8 m2﹒g-1 respectively. It was postulated that the better textural properties of zirconia containing Y or Ce were resulted from preventing zirconia particles sintering in the presence of Y or Ce additive. All of these samples made by SCD had a well-developed mesoporous texture.     

氧化铈气凝胶担载的铜催化剂对氢气中一氧化碳选择氧化的催化性能

以超临界干燥法制备了氧化铈气凝胶,并以此为载体用浸渍法制备了铜催化剂.利用色谱流动反应法进行了活性测试,测试表明该催化剂对于富氢气氛中的CO选择性氧化具有较高的催化活性和较好的选择性,其中CuO的负载量为12.23% (质量分数)的催化剂对CO氧化的催化活性最高,且该催化剂在低空速下具有较好的抗H2O和抗CO2性能.     

氧化铜/氧化锆甲醇合成催化剂的性能研究

以超临界干燥法制得的超细ＺｒＯ２为载体，浸渍铜后所得的ＣｕＯ／ＺｒＯ２催化剂对ＣＯ／Ｈ２合成甲醇呈现出较好的活性选择性，反应温度对催化剂的活性和选择性有较大的影响，ＸＰＳ结果表明，载体和活性组分间存在着相互作用，ＴＰＲ结果说明ＣｕＯ／ＺｒＯ２中的铜以两种形式存在，一种为体相铜，另一咱为高度分散的铜，后者的含量和甲醇产率存在着顺应关系，它应是关键的活性组分。     

二-(2-乙基己基)磷酸在不同稀释剂中对钼(Ⅵ)的萃取

考察了Mo(VI)在盐酸水相与二-(2-乙基己基)磷酸的不同稀释剂有机相间的分配平衡,观察到萃取平衡常数按正辛烷、四氯化碳、苯、氯仿、1,2-二氯乙烷、甲苯、甲基异丁基酮的次序递减,萃合物的组成也按这一顺序呈现规律性变化.文中将这些结果与稀释剂极性进行了关联,得到萃取平衡常数与稀释剂的极性参数E_T间良好的线性关系.此外,本文还提出了H_2MoO_4的酸、碱式解离常数分别为0.158和1.21×10(-13).     

超细二氧化锆的制备和表征

通过研究不同干燥条件下制得的二氧化锆的织构和结构，发现在超临界干燥过程中附加一定的惰性气体压力能够防止或大大减小凝胶在干燥过程中的收缩，从而可提高ＢＥＴ表面积，和普通空气中干燥得到的二氧化锆相比，超临界干燥得到的二氧化锆的孔结构大为改善。同时ＢＥＴ表面积地增大。     

制备方法对La改性的Ni/γAl2O3催化甲烷部分氧化的研究

采用共沉淀法和浸渍法制备La改性的Ni/γAl2O3催化剂，并用于催化甲烷部分氧化反应。共沉淀法制备的催化剂表现出较高的活性和稳定性。空速为80000h－1、800℃时甲烷的转化率接近100％，H2的选择性达99.8％，且在稳定性实验中保持15h活性变化不大。实验采用BET、TPR和XRD说明共沉淀法制备的镍基氧化铝催化剂中，La的加入提高了催化剂的比表面积，有效的抑制了大颗粒NiAl2O4的形成，降低了催化剂活性组分的还原温度，对POM显示出很高的催化活性。     

高分子纳米复合材料拉伸及压缩的分子动力学模拟

利用高分子-纳米粒子粗粒化模型,对高分子纳米复合材料(polymer nano-composites,PNC)的拉伸、压缩及平衡态过程进行分子动力学模拟研究.通过模拟PNC的拉伸及压缩过程,研究纳米粒子大小、质量分数对PNC力学性能的影响及拉伸、压缩过程中PNC体系微观交联网络的变化.在纳米粒子表面积或质量分数相同的情况下,小尺寸纳米粒子对PNC的力学性能增强效果更显著.对于含有质量分数不同的小尺寸纳米粒子的PNC体系,随纳米粒子质量分数增加,其力学性能增强,但增强程度逐渐减弱,且对于拉伸过程的材料增强效应,纳米粒子的质量分数存在最优值.在PNC体系中存在高分子-高分子(polymer-polymer)、高分子-纳米粒子(polymer-NP)2种微观交联网络,拉伸及压缩过程中PNC体系中2种微观交联网络的变化趋势不同,PNC拉伸及压缩产生应力的微观机制也相应有所不同.此外,对含质量分数不同的小尺寸纳米粒子的PNC平衡态过程的模拟研究表明,PNC体系中2种微观交联网络的比例直接影响其力学性能的变化,而纳米粒子的聚集则会降低PNC的力学性能增强效果.