Study of adsorption of oxygen on β-Al2O3 + Au and β-Al2O3 + Pt: Work function measurements—proposition of a model

To improve the understanding of the electrochemical effects observed on an original potentiometric gas sensor, interactions of oxygen with the device were investigated. This gas sensor is made of a solid electrolyte (treated Na-β-alumina) associated with two metallic electrodes (gold and platinum) located in the same gas mixture. Adsorption of charged oxygen species, considered responsible for the electrical response developed by the sensor, was investigated by work function measurements. Results showed that charged oxygen species only form on partially gold or platinum covered solid electrolyte. Comparison of these results with those obtained in a previous calorimetric study of interactions between oxygen and the same materials suggests the existence of at least two different oxygen species adsorbed on the surface of the sensitive element. The first one, located on the solid electrolyte surface, is neutral and characterized by an endothermal reaction of formation. The second one is charged and probably produced at the gas/solid electrolyte/metallic electrode interface. A mechanism based on the concept of “three phase boundary” and similar to the “reverse spillover” phenomenon is proposed to account for the adsorption of these oxygen species.     

吸附溶出伏安法测定毗喳酮的研究

本文报道了用吸附溶出伏安法测定毗喳酮.以悬汞电极为工作电极，在Na}B,O,-NaOH介质(pH=10)中，毗喳酮产生一尖锐的吸附还原峰,E，二一1. 29V (vs. SCE )，峰电流与毗喳酮浓度在2. 0 X 10-'-8. 0 X 10-smol " L-’范围内呈良好的线性关系.检测限为2. 0 X 10-0mol " L-'(富集90s).本文对毗喳酮在悬汞电极上的电化学行为进行了探讨，对测定毗喳酮的最佳条件进行了详细的选择，利用本法测定了片剂中毗喳酮含量，结果满意.     

利用CARS方法研究超短脉冲激光的脉冲宽度

在理论上提出了利用两光束CARS/CSRS方法测量超短脉冲激光的三阶相关函数。实验上在几种样品中测量了CARS/CSRS的时间特性,得到了泵浦光脉冲,SCDL输出光脉冲以及受激喇曼散射光脉冲的宽度。     

有机薄膜器件负电阻特性的影响因素

研究了影响有机染料掺杂聚合物薄膜器件负电阻特性的因素，为探索有机负电阻的机理提供实验依据。实验中制备了多种有机染料掺杂聚合物薄膜器件，研究了有机小分子染料、聚合物基体、薄膜组成及厚度、ITO和聚苯胺阳极等对有机染料掺杂聚合物薄膜器件负电阻特性的影响。在室温、大气环境下，所制备的多种有机染料掺杂聚合物器件在所加电压为3～4V时，观察到明显的负电阻特性，电流峰谷比最大约为8。负电阻现象及峰谷比的大小受膜厚和器件的结构、制备工艺等影响。提出用负电阻和二极管并联组成的等效电路模型解释影响负电阻特性的因素，认为负电阻特性与载流子的不平衡注入有关。在此基础上设计、合成了主链含唔二唑电子传输基团的可溶性聚对苯撑乙烯衍生物，该聚合物兼具空穴和电子传输功能，在空气中具有较稳定的N型负电阻特性。进一步控制相关材料和工艺条件，有可能得到易于控制的负阻效应，开发出新型的有机负电阻器件。     

用紧耦合方法研究C4+和O6+与He原子碰撞

用双中心原子轨道紧耦合方法计算了C4+-He以及O6+-He碰撞的单俘获总截面,入射离子的能量范围为10～100keV/amu,所得计算结果在实验误差范围内与实验值很好符合.对满壳层入射离子,研究了单俘获截面随入射离子电荷态的变化,并讨论了原子轨道展开波函数数目对计算结果的影响.p     

Heat of adsorption and density distribution in slit pores with defective walls: GCMC simulation studies and comparison with experimental data

The adsorption behavior (capacity, density distribution and packing density) and the isosteric heat versus loading in a slit pore whose walls contain defective graphene layers are investigated in this paper. The defective wall is characterized by the extent and size of the defect. Simulation results obtained with the Grand Canonical Monte Carlo method reveal complex patterns of isosteric heat, and this complex behavior is a result of the interplay between three factors: (i) the surface heterogeneity (solid-fluid interaction, sites with varying degree of affinity), (ii) fluid-fluid interaction and (iii) the overlapping of potentials exerted by the two defective walls. We illustrate this with argon adsorption in pores of various sizes, and results obtained from the simulation agree qualitatively with the experimental data at 77 K on Saran microporous S600H and micro-mesoporous S84 charcoals of Beebe et al. [R.A. Beebe, B. Millard, J. Cynarski, J. Am. Chem. Soc. 75 (1953) 839]. The S600H was found to contain pores predominantly in the neighborhood of 7 Å with 30% of defect and a defective size of 2.84 Å. This is consistent with the argument made by Beebe et al. that this sample is a microporous solid and most pores can accommodate only one layer. The other sample, S84, has larger pores than S600H, and it is found that it has a wider pore size distribution and the pore width is centered at about 12 Å.     

Enzymes immobilized on montmorillonite: comparison of performance in batch and packed-bed reactors

Summary The enzymes a-amylase, invertase and glucoamylase were immobilized on acid activated montmorillonite using two techniques, viz. adsorption and covalent binding, and their activities were tested in a batch and packed-bed reactor and were compared. The packed-bed reactor showed an improved performance for all immobilized enzymes, which was attributed to lowering of diffusional restrictions to mass transfer. Lower activity in case of batch reactor for immobilized invertase was due to a combined effect of loss of native conformation of enzyme on account of immobilization and mass transfer resistances due to improper diffusion of substrate to the active site of enzyme. For immobilized glucoamylase, the packed-bed reactor demonstrated exceptionally high activity that was very close to the free enzyme. Covalently bound glucoamylase showed higher activity than the free enzyme.     

Ⅰ类超晶格势阱中能级分布及电子跃迁规律研究

在研究大量实验曲线的基础上,指出势阱所有能级均有一定的宽度,电子或空穴在各能级中出现的概率符合正态分布,从理论上分析了I类超晶格和双势垒单势阱的发光光谱与吸收光谱·解释了GaAs/Ga1-xAlxAs多量子阱和超晶格吸收光谱吸收边及量子阱变窄时各吸收峰的“蓝移现象”及GaAs/Ga1-xAlxAs双势垒单量子阱样品的电流—电压特性曲线及电导—电压特性曲线的特征和出现的“负阻效应”·     

现场拉曼光谱研究乙腈在金电极上的解离吸附行为

利用共焦显微拉曼系统、结合合适的电极表面粗糙方法研究了非水体系 0 1mol/LLiClO4 /CH3CN溶液中 ,乙腈分子在金表面的吸附和解离行为。结果表明非水体系中乙腈可在金表面发生还原反应 ,产物CN- 离子与电极表面作用形成的表面配合物可在较宽的电位区间吸附于电极表面。溶液中的微量水、激光照射以及电极电位均对该反应有较大的影响。通过拉曼谱图的比较得出乙腈分子解离出的CN- 在金电极表面比在银电极表面有更强的吸附作用。