CO在Cu表面吸附过程中电荷转移的理论研究

应用密度泛函理论．对CO分子在Cu(100)表面的吸附过程进行了研究。计算了CO分子以垂直方式在3种不同吸附位置吸附时CO分子和Cu(100)表面原子的电荷分布。结果表明：与碳原子最近邻的铜原子表面上发生明显电荷转移．而其他表面原子及体相原子的电子结构没有变化。Mulliken集居数及局域态密度分析表明，吸附过程中CO分子与表面Cu原子相互作用主要是CO分子内杂化轨道和3d，4s，4p(Cu)的贡献。     

表面活性剂在非织造布表面的吸附

选用不同类型表面活性剂水溶液对涤纶、丙纶非织造布进行了处理,发现表面活性剂在非织造布表面的吸附主要是在纤维交叉处,且以垂直纤维表面定向排列的形式吸附。从毛细管上求得的阳、阴、非离子型表面活性剂的吸附等温线各不相同。１２２７的吸附等温线出现最大值;ＬＡＳ和ＯＩＩ－１０的吸附等温线分别近似于Ｂｒｕｎａｕｅｒ的第五种和第四种类型吸附等温线。吸附需经历一段时间才能达到平衡。对于同种吸附质和吸附剂,达到吸附     

表面改性活性炭对CO2的吸附性能

研究了用Ｈ２Ｏ２，ＨＮＯ３加醋酸铜溶液进行表面改性后的活性炭对ＣＯ２的吸附性能，分析了改性前后的活性炭的表面化学性质，测定了２７３Ｋ下的吸附等温线，用Ｄ－Ａ方程对吸附等温线进行了很好的拟合，探讨了表面改性对活性炭表面化学性质的影响及其表面化党性民吸附性能之间的关系。     

分子和表面吸附系统振动频率的理论计算研究

用ＡＳＥＤ－ＭＯ方法计算分子及表面吸附系统在平衡点附近的总能量．用二次多项式、三次多项式和两种形式Ｍｏｒｓｅ势能展开式模拟能量变化以求出力常数，从而得到振动频率．计算结果表明：在势能展开式中引入非对称项是振动频率结果得到较大改善的关键．本文进一步讨论了用Ｍｏｒｓｅ势、ＡＳＥＤ－ＭＯ方法计算的Ｃ２Ｈ２－Ｓｉ（１００）、Ｃ２Ｈ４－Ｓｉ（１００）吸附系统的振动频率，计算结果与实验结果符合得很好，从而支持了ＨＲＥＥＬＳ提出的上述分子在Ｓｉ（１００）－２×１表面的吸附结构．     

吸附过程中甲烷分子和煤表面的作用

采用气体临界参数确定甲烷分子势,并计算出3倍甲烷分子直径内的分子势函数。结合甲烷分子的正三角锥、倒三角锥吸附模型和煤表面的势垒,运用量子力学的理论,考虑极限条件下甲烷分子的经典力学特点,建立了甲烷分子在煤表面吸附势作用下的波动方程。同时考虑到甲烷分子虽然不间断地在煤表面吸附和解吸、单个分子的运动是时间的函数,但甲烷分子在煤表面吸附总量与时间无关,故将平面波动方程中的时间和距离作为两个独立变量,基于这种简化求出甲烷分子平面波动方程的特解。该研究为探索煤表面与甲烷分子间的作用机理及形式奠定了理论基础。     

阳离子表面活性剂在石英表面吸附行为的分子动力学模拟

为深入了解支链化对阳离子表面活性剂在水/石英界面吸附性质的影响,用分子动力学方法模拟十六烷基醚羟丙基季铵盐(C₁₆PC)和支链十六烷基醚羟丙基季铵盐(C_<sub>16GPC)在水/石英界面的单层和双层吸附行为,分析了不同浓度(即分子排列紧密程度)下表面活性分子的倾斜角、界面层厚度、水分子和尾端碳原子密度排布。结果表明：C_<sub>16GPC在较低浓度(分子平均占有面积0.466 nm²)形成紧密的吸附单层,明显低于C₁₆PC(0.272 nm²),说明支链结构有利于阳离子表面活性剂在水/石英界面的吸附,且在高浓度下C_<sub>16GPC被压缩的优先顺序依次为：主链>长支链>短支链。直链的C₁₆PC在较紧密的吸附单层上形成类似半胶束的双层结构;而支链的C_<sub>16GPC则是通过上下层长支链尾对尾的方式形成双层结构。     

Al在Si（111）面上吸附的ASED—MO研究

本文使用分子簇模型和原子交迭和电子离域-分子轨道(ASED—MO)方法,计算Al吸附在Si(111)面上不同位置的键长和键能(吸附能)。按照总能量最小原则,对铝吸附在硅表面层的顶位、中心位、再构中心位、迭位、再构迭位和桥位的不同位置,分别计称出Al—Si的键长为2.38、2.55、2.71、2.68、2.61和2.49×10~(-10)m;各位置对应的吸附能分别为0.72、0.37、0.40、0.01、1.02和0.62eV。另一方面,根据Al_3Si_(26)H_(26)分子簇的计算结果,得出3个铝原子吸附在Si(111)面上的最佳位置为相邻的双折(桥位)位置,同时由能量计算表明铝的复盖率为3/7单原子层。     

Oxygen adsorption on pyrite （100） surface by density functional theory

Pyrite (FeS2) bulk and (100) surface properties and the oxygen adsorption on the surface were studiedby using density functional theory methods. The results show that in the formation of FeS2 (100) surface, there exists a process of electron transfer from Fe dangling bond to S dangling bond. In this situation, surface Fe and S atoms have more ionic properties. Both Fe^2 and S^2- have high electrochemistry reduction activity, which is the base for oxygen adsorption. From the viewpoint of adsorption energy, the parallel form oxygen adsorption is in preference The result also shows that the state of oxygen absorbed on FeS2 surface acts as peroxides rather than O2.     

Study on hydrogen atom adsorption and diffusion properties on Mg (0001) surface

Hydrogen atom adsorption and diffusion properties on clean and vacancy defective Mg (0001) surface have been investigated systematically by using a first-principles calculations method based on the density functional theory. The calculation results of adsorption energy and diffusion energy barrier show that hydrogen atom is apt to be adsorbed at fcc and hcp sites on clean Mg (0001) surface, and fcc adsorption site is found to be more preferred. The highest diffusion energy barrier is estimated as 0.6784 eV for the diffusion of hydrogen from clean Mg (0001) surface into its bulk. Surface effects, which affect hydrogen diffusion obviously, results in a slow diffusion velocity of hydrogen from surface to subsurface, while a fast one from subsurface to bulk, indicating the range of surface effects is only restricted within two topmost layers of Mg (0001) surface. Comparatively, Mg atom vacancy on Mg (0001) surface not only enhances the chemisorption interaction between H and Mg surface, but also benefits H atom diffusion in Mg bulk with relatively more diffusion paths compared with that of clean surface. Besides, hydrogen atom is found to occupy mostly the tetrahedral interstice when it diffuses into the Mg bulk. Further analysis of the density of states (DOS) shows that the system for hydrogen atom to be adsorbed at fcc site has a lower DOS value (N (E _F)) at Fermi level and more bonding electrons at the energy range blow the Fermi level of H/Mg (0001) system as compared with that at hcp site. On the other hand, the enhanced chemisorption interaction between hydrogen and defective surface should be attributed to the fact that the electronic structures of Mg (0001) surface are modified by an Mg vacancy, and the bonding electrons of the topmost layer Mg atoms are transferred from low energy range to Fermi level, which is in favor of improving the surface activity of Mg (0001) surface. Supported by the PhD Programs Foundation of Ministry of Education of China (Grant No. 200805321032), the Science and Technology Program Project of Hunan Province (Grant No. 2008GK3083) and the Program for Changjiang Scholars and the Innovative Research Team in university (Grant No. 531105050037)     

Ar^＋离子轰击对GoAs（100）表面的影响

采用X射线光电子谱(XPS)和紫外光电子谱(UPS)着重研究了GaAs(100)表面由于Ar~+离子轰击而导致的功函数变化及Ga3d,As3d能级变化。从中仔细分析由于Ar~+离子轰击n—GaAs(100)表面的能带弯曲,结果表明,不同能量Ar~+离子轰击后,Ga3d及As3d的位移峰结合能变化可达0.3eV,同时功函数也变化相同的值。而且在不同温度下尽管采用同一能量Ar~+离子轰击。GaAs(100)表面功函数也有明显的差别。但是,在低温下(—120℃左右),采用不同能量的Ar~+离子轰击GaAs(100)表面,GaAs(100)表面仍有相同的功函数。     

乙醇——水气相吸附过程的研究 (一)吸附平衡

本文是在研究以多醣类物质作吸附剂制取无水乙醇的新工艺基础上,采用迎头色谱法测定了吸咐等温线,突验数据通过回归分析,获得符合Freundlich型的吸咐等温方程,计算值与实验结果吻合较好。实验还证明了多醣类物质在实验的温度范围内,选择性地吸附水蒸汽,而不吸附乙醇蒸汽。     

硝基苯在两种不同吸附树脂上的吸附动力学研究

研究了硝基苯在HZ-816树脂和H-103树脂上的吸附动力学,结果表明,硝基苯在两种树脂上的吸附平衡时间都很短(4 h),吸附符合Lagergren一级吸附动力学方程;温度对吸附平衡影响较小,初始浓度影响较明显.静态脱附实验表明,甲醇是理想的脱附剂.     

乙醇——水气相吸附分离工艺的研究

本文是以不同于传统方法的气相吸附法制取无水乙醇,所用吸附剂为多糖类物质,它仅吸附水,几乎不吸附乙醇.该法在吸附和再生时,能耗均相当低。文中讨论和测得了最佳工艺操作条件,获得无水乙醇,其质量主要指标达到试剂化学纯的要求.     

双组分协同吸附的非线性色谱波动特征

为了深入理解协同吸附过程的色谱规律，运用特征线法分析了双组分协同吸附色谱的3种不同类型
，构造了饱和过程和洗脱过程的浓度波动图像,并与竞争吸附色谱过程做了比较.结果表明,协同吸附色谱
过程的熵条件与竞争吸附情况下有很大不同；对于双组分协同吸附的3种不同类型，当强吸附组分具有或
强弱吸附组分都具有协同吸附效应时，可以由特征线法得到解析解；当只有弱吸附组分具有协同效应时
，色谱方程为混合型方程，特征线法失效；对饱和过程和洗脱过程的分析表明，协同效应不改变组分的
分离顺序，但改变了熵条件，使得浓度波性质和波动图像随之改变.     

The theoretical study of O<Subscript>2</Subscript> adsorption on NiTi (100) and (110) surfaces

The discrete variational Xa method (DV-Xα) within the framework of density-functional theory was applied to study O₂ molecule adsorption on NiTi (100) and (110) surfaces. The bond order and charge distribution between Ti and O atoms for two possible O₂ molecule adsorption ways on NiTi (100) and (110) surfaces were calculated. It is found that the adsorption way for O−O bond perpendicular to NiTi surface is preferred to that for O−O bond parallel to NiTi surface, and O₂ molecule only interacted with one nearest surface titanium atom during the adsorption process. Mulliken population and the partial density of state analysis show that the interaction between Ti and O atoms is mainly donated by O 2p and Ti 4s electrons on NiTi(110) surface, O 2p and Ti 4s, 4p electrons on NiTi(100) surface, respectively. The total density of state analysis shows that NiTi(100) surface is more favorable for O₂ molecule adsorption. HUA Ying-jie: Born in 1966. Funded by the National Natural Science Foundation of China (No. 50081001)