银-铂合金表面吸附氧的热脱附谱

用热脱附谱研究了氧在银-铂合金(含Pt 9.7 at.%)表面上的化学吸附。结果表明:氧在合金表面上主要存在两种吸附状态,峰温为580±10K的二级脱附峰,与氧原子在合金表面Ag原子上的吸附相对应,脱附活化能E_d=213±15kJ/mol;峰温在660K左右的二级脱附峰,与合金表面Pt原子对氧的作用有关,脱附活化能为330～430kJ/mol,并随氧暴露量的增加而增大。     

CH_3OD在Si(111)表面上的TDS研究

本文运用热脱吸附谱方法(TDS)研究了室温下CH_3OD在Si(Ⅲ)表面上的吸附,对所取得的H_2, HD及D_2的热脱吸附谱进行了分析和比较,并计算出它们的脱吸附能和预指数因子.     

苯在Silicalite-1分子筛上的吸附和脱附

采用重量法研究了苯在silicalite-1分子筛上303K时的吸附和室温至400.C的热脱附行为.结果表明苯在303 K时的吸附和脱附等温线有两个台阶,并且出现了滞后环.DTG曲线展示了当每单位晶胞吸附量小于4个分子时只有一个热脱附峰;而当每单位晶胞吸附量大于4个分子时有两个热脱附峰,并且在TG曲线上每单位晶胞吸附量为4个分子处有一个拐点.DTG曲线揭示了苯在silicalite-1上存在两种吸附位置,吸附在不同位置上的分子之间存在平衡关系,不同升温速率对热脱附几乎无影响.     

Kinetic Monte Carlo方法对薄膜生长初期表面形貌的研究

用Kinetic Monte Carlo方法研究了薄膜生长初期的表面形貌, 对激活能的计算采用了更加通用、准确的算法, 模型考虑了原子吸附、迁移、脱附、蒸发原子返回基底, 二体运动等多种机理, 根据模型编写了相应的软件, 利用计算机图形学的原理对薄膜的表面形态进行了三维立体成像, 并通过模拟发现, 在低温和高温时薄膜的早期成核和表面形貌完全不同, 薄膜后续的生长与早期成核有很大的关系. 微观机理主要受原子的热运动影响, 温度决定扩散能力, 入射率决定扩散时间.     

用光电子能谱研究甲酸在Cu(110)氧化表面的吸附态

甲酸在洁净Cu(110)表面的吸附态为HCO0~-(a);在氧化后呈现(2×1)和c(6×2)LEED花样的表面,甲酸使表面氧O~(2-)(a)加氢成水脱附,然后以HCOO~-(a)形态吸附在表面.在严重氧化的Cu(110)表面有三层以上的Cu_2O,甲酸将最上层的O~(2-)(a)加氢成水脱附,产生Cu(0)-O-Cu(I)活性中心,使甲酸以H_2CO形态吸附在表面上.由此可见在铜锌铝甲醇合成催化剂中,能与Cu(I)-O配位的Cu(0)原子,是使中间物HCOO~-(a)加氢脱水的活性中心.     

甲醛在Ag(110)面上的非均相氧化

用热脱附谱、低能电子衍射和电子诱导脱附离子角度分布(ESDIAD)研究了甲醛与氧在Ag(110)面上的吸附和反应。结果表明,低温条件下每个吸附态氧原子能稳住几个甲醛分子,其中大部分在220K时以甲醛形式脱附。ESDIAD照片(225K)进一步证明了HCOOH_(a)中间体的存在,该中间体在235K进一步脱氢,在晶体表面上留下较稳定的吸附态甲酸脂(HCOO_(a))。在250K还出现一个水脱附峰和一个较小的甲醛脱附峰。吸附态甲酸脂在395K分解成CO_2和H_2。对反应机理作了探讨。     

H2在金属钾修饰碳纳米管上的吸附与储存

利用高压容积法、辅以卸压升温脱附排水法,测定金属钾修饰多壁碳纳米管(K~0-MWCNTs)对H_2的吸附储存容量。结果表明,在室温(～25℃)、～7.25MPa实验条件下其对氢的吸附储存容量可达3.80％(质量百分数);室温下卸至常压的脱附氢量为3.36％(占总吸附氢量的～89％),后续升温(升至673K)的脱附氢量为0.41％(占总吸附氢量的～11％)。     

用场发射涨落法研究原子在金属单晶面上的表面扩散

本文介绍了用场发射涨落法研究吸附原子(或分子)在金属单晶面上表面迁移的原理、实验装置和方法以及所取得的新的研究结果。这些研究结果包括:吸附的气体(H_2,O_2,CO等)在W(110)面上的表面扩散;吸附的气体(H_2)在Ni(100)面上的表面扩散;在较高温度时钨台阶表面上钨原子的表面自扩散和热租糙化过程的研究等。     

用光电子能谱研究金属锰、镁表面与甲醇、乙醇反应

用XPS和UPS法研究金属Mn、Mg表面与CH_3OH、C_2H_5OH的反应,室温下,ROH(R=CH_3,C_2H_5)以RO~-的形态吸附在Mg表面,Mn表面有较高的活性,ROH除以RO~-的形态被吸附外,部分还分解为O~(2-)和脱附的碳氢化合物,加热至600K时,Mn表面RO~-完全分解为O~(2-)和R,后者与表面氢结合后脱附,部分C_2H_5O~-中的碳成无定形碳并在～675K加氢脱附,ROH在氧化锰表面除以RO~-的形态被吸附外,在高于650K时还产生CH_2O_(a)、C_2H_4O_(a)等,这些物种在700K依然存在,氧化使锰表面断裂R—O和C—C键的活性降低而其脱氢活性仍然存在。     

大幅度降低金属焊接温度的技术

日本金属材料技术研究所最近开发了在比过去低几百度的温度下进行焊接的技术。该新技术是在焊接前把金属材料置于真空中预加热,消除表面氧化膜,使金属中含的硫渗出到硫层为1个原子左右薄,可阻止表面上氧炭的吸附,焊接时不会在金属内扩散,     

Preparation and properties of the SmOx/Rh(100) model surface

The preparation of SmOx/Rh(100) and CO adsorption on this model surface have been investigated with Auger electron spectroscopy (AES), X-ray photoelectron spectroscopy (XPS) and temperature programmed desorption spectroscopy (TDS). The oxygen adsorption on the SmRh alloy surface leads to the aggregation of Sm on the surface. The thermal treatment of this oxidized surface induces the further agglomeration of SmOx on the Rh(100) surface. Compared with CO TDS on the clean Rh(100) surface, three additional CO desorption peaks can be observed at 176, 331 and 600 K on the SmOx/Rh(100) surface. The CO desorption peak at 176 K may originate from CO adsorbed on SmOx islands, while the appearance of the CO adsorption peaks at 331 and 600 K, depending on the oxidation state of Sm, is attributed to CO species located at the interface of SmOx/Rh(100).     

Preparation and properties of the SmOx/Rh(100) model surface

The preparation of SmO_x/Rh(100) and CO adsorption on this model surface have been investigated with Auger electron spectroscopy (AES), X-ray photoelectron spectroscopy (XPS) and temperature programmed desorption spectroscopy (TDS). The oxygen adsorption on the SmRh alloy surface leads to the aggregation of Sm on the surface. The thermal treatment of this oxidized surface induces the further agglomeration of SmO_x on the Rh(100) surface. Compared with CO TDS on the clean Rh(100) surface, three additional CO desorption peaks can be observed at 176, 331 and 600 K on the SmO_x/Rh(100) surface. The CO desorption peak at 176 K may originate from CO adsorbed on SmO_x islands, while the appearance of the CO adsorption peaks at 331 and 600 K, depending on the oxidation state of Sm, is attributed to CO species located at the interface of SmO_x/Rh(100).     

稀土氧化物对甲烷催化氧化的分子束研究

通过分子束与表面散射实验确定甲烷在Ｌａ２Ｏ３清洁表面是平动能激活吸附，阈值平动能５３．４８ｋＪ／ｍｏｌ。氧在Ｌａ２Ｏ３清洁表面的吸附服从Ａｒｒｈｅｎｉｕｓ方程关系，其脱附峰在９６０Ｋ。     

First-principles investigation on initial stage of 2H-SiC(001) surface oxidation

We present comprehensive first-principles calculations on the initial stages of SiC oxidation by atomic oxygen on the 2H-SiC(001) surface. In order to study the kinetics of oxygen incorporation at the 2H-SiC(001) surface, we investigated adsorption and diffusion of oxygen atoms and SiO₂ nucleation. The adsorption sites, corresponding to the local minima of the potential energy surface (PES) for isolated adatoms, were identified through a comparative study of the adatom binding energy at different locations. We found that the Bridge (siloxane) site is preferred over other adsorption sites. There is no energy barrier at 0K for oxygen insertion into this site. The diffusion energy barriers that the adatom has to overcome when jumping between two adsorption sites were calculated. The premises of silica nucleation were investigated by calculating the modifications of the oxygen atom binding energy due to the interaction with neighboring adatoms. Supported by Snecma Propulsion Solide (Contract FPR No. 0539298A), Natural Science Foundation of China (Grant No 50802076) and Flying Star Program of Northwestern Polytechnical University of China     

生活饮用水中二氧化氯快速测定方法研究

水中二氧化氯与N,N-二乙基对苯二胺（DPD）反应产生粉色,其中二氧化氯中20%的氯转化成亚氯酸盐,显色反应与水中二氧化氯含量成正比,甘氨酸将水中的氯离子转化为氯化氨基乙酸而不干扰二氧化氯测定。研究了快速测定生活饮用水中二氧化氯的方法——DPD现场测定法,实验证明该方法快速、适用、准确、灵敏度高。     

用格点法研究银或银金合金表面上氧的吸附规律

对混合式格点法作了进一步的改进，并用这一改进方法研究了氧在银或银合金表面上的吸附，结果表明：氧分子在银表面上发生吸附的阈值约为６．５ＫＪ．ｍｏｌ＾－１；氧分子动量大于４５ａｕ或合金中金的质量分数大于０．３时，都不发生分子氧的吸附，另外，处在振动激发态的氧分子比在振动基态的更容易发生吸附。     

TiO_2纳米管对Cu(Ⅱ)和Ag(Ⅰ)的吸附和光催化还原作用研究

以纳米TiO2为原料,采用水热合成法制备TiO2纳米管.FT-IR表征表明含有较为丰富的羟基;XRD表征表明TiO2纳米管主要为锐钛矿相,有少量的金红石相;BET比表面积为96.5m2.g-1.TiO2纳米管吸附Cu(Ⅱ)和Ag(Ⅰ)的结果表明,吸附符合朗格缪尔吸附等温线模型,Cu(Ⅱ)和Ag(Ⅰ)的qmon分别为2.41×10-5、13.3×10-5 mol.g-1,K分别为3.95×103、6.35×103 L.mol-1.在300W的紫外灯照射下进行光催化实验,结果表明反应近似符合一级模型,反应级数与金属离子在TiO2纳米管表面的吸附平衡常数相关;TiO2纳米管对Cu(Ⅱ)和Ag(Ⅰ)具有较高的光催化活性.     

Hydrogen Adsorption on Metal-Organic Framework MOF-177

This review summarizes the recent literature on the synthesis, characterization, and adsorption properties of meal-organic framework MOF-177. MOF-177 is a porous crystalline material that consists of Zn4O tetrahedrons connected with benzene tribenzoate (BTB) ligands. It is an ideal adsorbent with an exceptionally high specific surface area (BET4500 m2/g), a uniform micropore size distribution with a median pore diameter of 12.7 ?, a large pore volume (2.65 cm3/g), and very promising adsorption properties for hydrogen storage and other gas separation and purification applications. A hydrogen adsorption amount of 19.6 wt.% on MOF-177 at 77 K and 100 bar was observed, and a CO2 uptake of 35 mmol/g on MOF-177 was measured at 45 bar and an ambient temperature. Other hydrogen properties (kinetics and heat of adsorption) along with adsorption of other gases including CO2, CO, CH4, and N2O on MOF-177 were also be discussed. It was observed in experiments that MOF-177 adsorbent tends to degrade or decompose when it is exposed to moisture. Thermogravimetric analysis showed that the structure of MOF-177 remains intact at temperatures below 330℃ under a flow of oxygen, but decomposes to zinc oxide at 420℃.     

HREELS study on coadsorption of oxygen and cyclohexanone on the Pt(111) surface

The coadsorption of cyclohexanone and oxygen on Pt(111) has been investigated by HREE-LS and TDS. At 205 K the presence of oxygen induces an “extra” red-shift of the C = O stretching of coadsorbed cyclohexanone. Heating this coadsorbed surface from 205 to 250 K leads to further dehydrogenation to form intermediate species and to complete disappearance of the C = O stretching band. Above 300 K, the molecule rings of dehydrogenation species cleave to form hydrocarbon fragments and CO molecules which directly desorb into the vacuum or react with preadsorbed oxygen to produrn CO₂ which leave the surface immediately. TDS results provide further evidence that the preadsorbed oxygen promotes the decomposition of cyclohexanone.     

青海地表砂性氯盐渍土溶陷特性试验

为研究氯盐渍土的溶陷特性及其影响因素,以青海地区铁路沿线砂性氯盐渍土为依托,以初始含水率、氯盐含量、压实度及起始溶陷压力为四个主要影响因素,进行了室内正交试验。探究了以上四个影响因素对溶陷的影响程度;并通过三维曲面散点图对其进行拟合,定量分析了这四种影响因素对氯盐渍土的影响关系;论证了青海地区锡铁山到北霍布迅地区铁路沿线地表土在铁路路基中的适用性。试验结果表明:氯化钠含盐量对溶陷影响最大,初始含水率次之,起始浸水压力和压实度影响最小;得到了地表土溶陷系数随初始含水率、含盐量、压实度、浸水荷载和溶陷系数的Rational Talor关系式。当列车时速不超过250 km·h~(-1)时,地表土可用作铁路路基填料;当车速超过300 km·h~(-1)时,不可用作高速铁路路基填料。