氧的同位素气体在NiO表面的热脱附的测定与分析

采用程序升温脱附实验方法测量氧的同位素C16O2,C18O2和18O2分别在Ni16O表面吸附后的脱附谱,其结果表明C16O2在Ni16O表面吸附后出现C16O2和C16O两个波峰,且C16O2和C16O的脱附量随C16O2气体暴露量增加而增加,其峰值温度随C16O2气体暴露量增加而减少,当C16O2气体覆盖度超过一定值后,C16O2和C16O脱附量趋于常数,其活化能分别是0.48 eV和0.42 eV。C18O2在Ni16O表面吸附后出现C16O2,C18O16O,C18O2三个波峰,这说明吸附气体C18O2与Ni16O表面发生氧同位素交换,随温度升高而脱附出C16O2;18O2在NiO表面吸附后主要以18O2脱附,说明了富18O2有相对抑制与Ni16O表面氧的同位素交换的作用。     

MlNi4Co0.6Al0.4储H2合金表面吸H2的TDS研究

用热脱附谱(TDS)对不同表面处理的富La混合储H2合金MlNi4Co0.6Al0.4粉末样品进行H2气吸附和脱附特性的比较和研究。未经表面处理的粉末样品,只测到一个H2脱附峰(α峰),脱附温度在400K左右;经6molKOH溶液,在80℃下处理6h的MlNi4Co0.6Al0.4粉末样品,有2个H2热脱附峰(β峰和γ峰),脱附温度分别在540和630K处;而用6molKOH+0.02molKBH4溶液处理后,则有3个H2热脱附峰(α峰,β峰和γ峰),脱附温度分别在400,530和640K处。TDS研究表明,热碱加还原的处理使材料表面对H2气吸附的活性和容量提高,并使各个吸附态的扩散和转变更加容易。     

气体脱附机理的物理解释

采用一组新的方程来分析抽气过程。这个方程基于气体分子在不均匀的金属表面上所取位置的吸附与脱附的表面,而不是扩散过程。分析脱附位置、脱附率和气体脱附的来源.认为气体脱附现象必须理解为非平衡和非稳定过程。     

椰壳类活性炭孔隙结构对苯并噻吩脱附活化能的影响

主要研究活性炭孔隙结构对苯并噻吩脱附活化能及吸附性能的影响.使用ASAP 2010测定了3种椰壳制活性炭SY-6、SY-13和SY-19的BET比表面及其孔隙结构,采用程序升温脱附技术(TPD)测定了苯并噻吩在3种活性炭上的脱附活化能,用静态吸附法进行了苯并噻吩在不同活性炭上的吸附等温线,并讨论了活性炭孔隙结构对苯并噻吩脱附活化能及吸附性能的影响.结果表明,3种活性炭SY-6、SY-13和SY-19的比表面积分别为1106、1070和689m2/g,其平均孔径分别为1.96、2.58和2.16nm.苯并噻吩在SY-6、SY-19和SY-13活性炭上的脱附活化能依次为58.84、53.02和42.57kJ/mol,3种活性炭对苯并噻吩吸附容量的大小依次为SY-6＞SY-19＞SY-13.活性炭平均孔径越小,其表面对苯并噻吩的作用力越大,苯并噻吩在其表面上的脱附活化能越大.Freundlich模型能够较好的来描述苯并噻吩在活性炭上的吸附.     

MlNi_4Co_(0.6)Al_(0.4)储H_2合金表面吸H_2的TDS研究

用热脱附谱 (TDS)对不同表面处理的富La混合储H2 合金MlNi4 Co0 6Al0 4 粉末样品进行H2 气吸附和脱附特性的比较和研究。未经表面处理的粉末样品 ,只测到一个H2 脱附峰 (α峰 ) ,脱附温度在 40 0K左右 ;经 6molKOH溶液 ,在 80℃下处理 6h的MlNi4 Co0 6Al0 4 粉末样品 ,有 2个H2 热脱附峰 (β峰和γ峰 ) ,脱附温度分别在 5 40和 6 30K处 ;而用 6molKOH 0 0 2molKBH4 溶液处理后 ,则有 3个H2 热脱附峰 (α峰 ,β峰和γ峰 ) ,脱附温度分别在 40 0 ,5 30和 6 40K处。TDS研究表明 ,热碱加还原的处理使材料表面对H2 气吸附的活性和容量提高 ,并使各个吸附态的扩散和转变更加容易。     

N2在多晶Ni表面电子诱导脱附的实验研究

电子诱导脱附是近年来在真空科学与表面科学领域内的热门研究课题。电子诱导脱附不仅作为研究和探讨原子激发过程以及电子能量传输机制的有效手段,而且已经逐渐成为获取表面和界面结构、状态等信息的有效方法。本文介绍了利用两种实验装置研究N2在多晶Ni表面的电子诱导脱附实验,测量了(1×10~(-3) Pa)条件下,N2在多晶Ni表面的脱附产额、电子诱导脱附阈值能量等重要的物理参量。实验研究工作不仅为进一步深入理解和探讨电子诱导脱附内在机制提供了直接的实验依据,而且对表面吸附状态、吸附-脱附过程等理论研究工作以及真空测量、电子轰击除气等工程应用工作都有重要意义。     

MINi4Co0.6Al0.4储H2合金表面吸H2的TDS研究

用热脱附谱（TDS）对不同表面处理的富La混合储H2合金MINi4Co0.6Al0.4粉末样品进行H2气吸附和脱附特性的比较和研究,未经表面处理的粉末样品,只测到一个H2脱附峰（α峰）,脱附 度在400K左右,经6mol KOH溶液,在80度下处理6h的MINi4Co0.6Al0.4粉末样品,有2个H2热脱附峰（β峰和γ峰）,脱附温度分别在540和630K处,而且6mol KOH 0.02mol KBH4溶液处理后,则有3个H2热脱附峰（α峰,β峰和γ锋）,脱附温度分别在400,530和640K处,TDS研究表明,热碱加还原的处理使表面对H2气吸附的活性和容量提高,并使各个吸附态的扩散和转变更加容易。     

啶虫脒在超高交联吸附树脂上的吸附及脱附性能研究

本文从动态和静态的角度研究了均苯四甲酸酐修饰的超高交联吸附树脂（PMAR）和1,2,4-苯三酸酐修饰的超高交联吸附树脂（TMAR）对啶虫脒的吸附和脱附行为。结果表明：两种树脂对啶虫眯的吸附和脱附效果都比较好,TMAR的静态吸附量为470．9mg·g^-1干树脂,饱和吸附量为562．7mg·g^-1干树脂;PMAR的静态吸附量为453．4mg·g^-1干树脂,饱和吸附量为559．1mg·g^-1干树脂。两种树脂都易于脱附,用2mol·L^-1 HCl：乙醇（体积比1：1）作脱附剂,温度323K,脱附剂体积为9．5BV（床体积）时,PMAR的脱附率为98．13％,TMAR的脱附率为99．83％。     

GaAs基片高温加热清洗过程中残气脱附的研究

为了优化GaAs基片的加热清洗工艺,获得原子级清洁表面,用四极质谱仪研究了GaAs基片高温加热清洗过程中常见气体及Ga、As元素的脱附规律.研究结果表明:常见气体(H2、H2O、N2、CO、CO2、Ar、CxHyOz)在100℃左右开始大量脱附;Ga、As元素主要以单质和氧化物的形态脱附,其脱附的温度存在两个峰值,分别是300℃和600℃;研究还发现真空环境中某些常见气体的含量会影响到Ga、As元素的脱附形式,当H2含量较高时,一部分As会以AsH3的形态脱附,当H2含量较低时,As基本以单质的形态脱附.经过多次实验及对实验结果的分析,最终确定了高温加热清洗的升温曲线及加热清洗的最高温度,获得了较为理想的原子级清洁表面.     

液态锂中氘脱附特性分析

锂化壁处理/液态锂第一壁可为托卡马克装置提供良好壁条件，但存在燃料滞留问题，为解决这一问题，需进一步研究氢同位素在液态锂中的脱附特性。本文设计了液态锂中气体吸附/脱附系统，开展了氘气在液态锂中的吸附实验，并分析了其脱附过程，通过采用微调阀调整进气速率的方式标定不同氘气分压下的系统抽速，计算了热脱附过程中气体的抽除量。结果表明，氘气在液态锂中的脱附峰温度在481℃附近，脱附的氘气仅有约36%被抽气系统抽除，剩余部分被壁面冷凝的锂重新吸附。该研究可为深入分析氘在液态锂中的脱附行为奠定良好基础，为未来解决液态锂中的燃料回收问题提供技术支持。     

不同助剂对合成甲醇工业催化剂二氧化碳加氢性能的影响

采用浸渍法制备了以工业铜基催化剂C301为基体,含CeO2、ZrO2、La2O3、MnO2、Pr2O3、SrO、V2O5助剂的一系列催化剂,在微型固定床反应器上考察了其对CO2加氢合成甲醇的催化性能及影响,并采用XRD、BET、H2-TPR和CO2-TPD等手段进行了表征。研究结果表明,除助剂Pr2O3外,CeO2、ZrO2、La2O3、MnO2、SrO、V2O5助剂的加入均促进了C301催化剂的CO2加氢合成甲醇活性,其中ZrO2的加入使CO2转化率提高了近5%,甲醇收率提高了近8%。     

Identification and quantitative studies of protein immobilization sites by stable isotope labeling and mass spectrometry

A method was developed for characterizing immobilization sites on a protein based on stable isotope labeling and MALDI-TOF mass spectrometry. The model for this work was human serum albumin (HSA) immobilized onto silica by the Schiff base method. The immobilized HSA was digested by various proteolytic enzymes in the presence of normal water, while soluble HSA was digested in (18)O-enriched water for use as an internal standard. These two digests were mixed and analyzed, with the (18)O/(16)O ratio for each detected peptide then being measured. Several peptides in the tryptic, Lys-C, and Glu-C digests gave significantly higher (18)O/(16)O ratios than other peptides in the same digests, implying their involvement in immobilization. Analysis of these results led to identification of the N-terminus and several lysines as likely immobilization sites for HSA (e.g., K4, K41, K190, K225, K313, and K317). It was also possible from these results to quantitatively rank these sites in terms of the relative degree to which each might take part in immobilization. This method is not limited to HSA and silica but can be used with other proteins and supports.     

Nitric oxide adsorption and desorption on alumina supported palladium

The adsorption properties of nitric oxide (NO) on alumina supported palladium were studied by a simultaneous thermogravimetric-analysis and differential-scanning-calorimetry (TGA-DSC) in a temperature ranges between 220 and 470 K. Upon adsorption, NO molecules on both Pd/Al2O3 and Pd/NaOH-Al2O3 samples were molecularly adsorbed between 220 and 300 K. Some NO molecules were strongly adsorbed on Pd/NaOH-Al2O3 and possessed a higher enthalpy of adsorption [approximately 140 kJ (mol NO)(-1)] than Pd/Al2O3 [approximately 114 kJ (mol NO)(-1)]. Upon heating above 320 K, the adsorbed NO molecule on these palladium surface was dissociated. In addition, a temperature programmed desorption and mass spectrometer (TPD-MS) study in a temperature range between 300 and 1100 K further indicated that some strongly adsorbed NO molecules may stay on basic sites (*b) and Pd-NaOH interface sites (*i) to enhance the decomposition of NO.     

R2O-MO-Al2O3-SiO2玻璃配方与热膨胀系数关系的支持向量回归研究

不同配方的玻璃一般具有不同的热膨胀系数.根据R2O-MO-Al2O3-SiO2(R为碱金属元素,M为碱土金属元素)系统玻璃在不同氧化物组成(SiO2,MgO,CaO,SrO,BaO,Na2O和K2O)下的热膨胀系数实测数据集,应用基于粒子群算法(PSO)寻优的支持向量回归(SVR)方法,建立了玻璃的不同配方与其热膨胀系数关系的SVR预测模型,并与基于BPNN神经网络模型的预测结果进行了比较.结果表明:对于相同的训练样本和检验样本,支持向量回归的玻璃的热膨胀系数模型始终比BPNN模型具有更高的预测精度;增加训练样本数有助于提高所建SVR预测模型的泛化能力;基于留一交叉验证法(LOOCV)的SVR预测的均方根误差(RMSE)、平均绝对误差(MAE)和平均绝对百分误差(MAPE)均为最小.本研究表明:SVR是一种预测不同配方玻璃的热膨胀系数的有效方法.     

Depth-profiling and diffusion measurements in ice films using infrared laser resonant desorption

A new infrared laser resonant desorption (LRD) technique has been developed that permits depth-profiling and diffusion measurements in ice. This LRD technique utilizes an Er:YAG rotary Q-switched laser with an output wavelength of lambda = 2.94 microm and a pulse duration of approximately 100 ns. The Er:YAG laser light resonantly excites O-H stretching vibrations in the H2O molecules that form the ice. This laser resonant heating induces H2O desorption at the ice surface. Control experiments were conducted on pure and isotopically mixed laminated ice films to determine the optimum experimental parameters for the LRD depth-profiling and diffusion measurements. Depending on laser energy, the measured desorption depth was either less than, comparable to, or larger than the optical penetration depth of approximately 0.8 microm at lambda = 2.94 microm. LRD studies were used to analyze H2 18O/H2 16O stacked multilayers and laminate sandwich structures. These measurements revealed that the LRD technique can depth-profile into ice films with submicrometer spatial resolution and high sensitivity. Two types of experiments employing LRD depth-profiling were demonstrated to monitor diffusion in ice. HCl hydrate diffusion in ice was measured versus time after depositing ice/HCl/ice sandwich structures. Na diffusion into ice was studied after adsorbing Na using a continuous Na source for a given exposure time at the diffusion temperature.     

Laser-induced surface decomposition of Al2O3 excited in the V-center absorption band

The primary products of desorption from Al₂O₃ surface excited by laser pulses (pulse duration τ∼15 ns; wavelength λ=354 nm, radiant power density P/S<10⁸ W/cm²) in the V-center absorption band were studied by the time-of-flight (TOF) spectroscopy. The TOF spectra show evidence of the desorption of one “ cold” (T ₁=300 K) and two “hot” (T ₂=1000 K, T ₃=4300 K) groups of oxygen molecules with the Maxwell velocity distributions, as well as of the hot Al and O atoms with nonequilibrium energy distributions (E ₁=0.37 eV, E ₂=0.38 eV). A model describing the oxygen desorption as initiated by the electron transitions is suggested, in which escape of the cold O₂ molecules from the surface is related to discharge of the O ₂ ⁻ anions adsorbed on the V-centers, desorption of the hot atoms is attributed to discharge of the surface O⁻ anions, and the appearance of the hot O² molecules is related to the associative desorption of two O⁻ anions localized at the same V-center discharged by a pair of excitons.     

Co-adsorption of CO and oxygen on W(110) surfaces

Influence of oxygen adsorption on CO chemisorption behavior over W(110) surfaces was studied using valence band spectra and thermal desorption spectroscopy (TDS). In the absence of O, CO formed a tilted and a vertical structure at 120 K on W(110). In the presence of O coadsorbate, in contrast, formation of the tilted structure of CO was suppressed. CO desorption from oxygen-covered W(110) surfaces showed indication of a strong interaction between adsorbates at ∼900 K, which was absent without O.     

SrO/CaO比对无碱铝硼硅酸盐玻璃热膨胀系数与低温特征粘度参考点的影响

恒定无碱铝硼硅酸盐玻璃中碱土金属氧化物的质量百分比不变,研究了SrO和CaO的相互替代对玻璃的热膨胀系数、应变点温度、玻璃转变温度、退火点温度、膨胀软化点温度等低温特征粘度参考点的影响。结果表明:玻璃的热膨胀系数随着n(SrO)/n(CaO)比值的增大而逐渐减小,低温特征粘度参考点在n(RO)/n(Al2O3)=0.96时达到极大值。