Hα线型分析

利用高斯分布拟合HT-6M托卡马克Hα线型，得出了由反射进入等离子体中的氢原子、氢分子离解后产生的氢原子，以及电荷交换产生的氢原子辐射Ｈα谱线的份额，由Doppler频移和展宽分别得出它们的入射速度和离子温度．在简化模型下讨论了氢原子的输运行为，得出了氢原子的密度分布和体发射系数，以及入射速度大小对粒子约束时间的影响，并与实验数据进行比较．由中性氢原子能量分布得出发生在边界的分子过程是氢分子的离解激发和电离离解 关键词：     

氢原子能量分布和分子过程

利用多道光学分析仪（ＯＳＭＡ）系统进行了高分辨率的Ｈα的测量,从Ｈα线型分布直接得出氢原子的能量分布,由能量分布可知发生在等离子体边界的原子、分子过程是离子在限制器表面中性化后的反射,以及电子碰撞引起的氢分子的激发离解和电离离解。     

HT—6M托卡马克边界粒子循环

利用光学多道分析仪系统进行了高分辨率的Ｈａ谱线线型的测量,从Ｈａ谱线线型直接得出氢原子的能量分布。由能量分布可知 ,发生在等离子体边界的原子,分子过程是离子在孔栏表面中性化后的反射,以及电子碰撞引起的氢分子的激发离解和电离离解。通过高斯拟合,得出了再循环粒的入射速度。     

表面氢对裂纹扩展的影响

暴露于含氢环境的金属表面会吸附氢原子,从而影响材料性能,一定情况下会导致氢脆.这篇文章主要通过分子动力学研究氢从α-Fe自由表面扩散到裂纹面的过程、和表面氢对裂纹扩展的影响.结果表明,在室温下,吸附在表面的氢原子很难直接从自由表面扩散到内部成为溶解氢;自由表面的氢原子会逐步向裂纹表面扩散,最后富集在裂纹表面和自由表面.当表面氢浓度较低时,氢对裂纹扩展影响很小,但是当裂纹表面的氢达到一定浓度时,会导致裂纹失稳扩展,造成严重的氢脆.     

高温高密度氢（氘）的物态方程——离解效应研究

 高温高压下流体氢将发生离解化学反应，形成具有相互作用的氢分子和氢原子混合体系，此时粒子间的相互作用复杂。利用单组分流体近似的范德瓦尔斯混合模型，将混合物粒子间的相互作用等效为单组分粒子间相互作用，从而简化了对体系的统计热力学处理；并由自由能函数极小化确定化学平衡时各组分含量、体系的内能、压强。研究了温度在10 000 K以下、密度在0.6 g/cm³以下（相应摩尔体积大于3.3 cm³/mol）区间的热致离解和压致离解现象对流体氢（氘）状态方程的影响。所得结果与双组分流体变分理论计算以及第一原理的分子动力学模拟、蒙特卡罗模拟结果以及二级轻气炮实验数据进行了比较，它们之间的一致性表明：用单组分流体近似的范德瓦尔斯混合模型处理氢（氘）分子的离解区域的物态方程是成功的。     

金属氢的高压合成机理

 从氢原子间及氢分子间的相互作用入手，提出了固体氢中氢分子在高压作用下解离为氢原子，并以氢原子相互结合成金属氢的微观转化过程的机理。用这样的转化机理，可以解释毛河光等关于固体氢的拉曼光谱频率随高压变化规律的实验结果。     

氢分子在Mg2Ni(010)面的吸附与分解

本文采用基于密度泛函理论(DFT)的第一原理赝势平面波(PW-PP)方法,对氢分子在Mg2Ni(010)面的吸附与分解进行了研究,我们发现氢分子以Hor1的方式吸附在表面层Ni原子的顶位时吸附能最高,为0.6769eV,这表明氢分子最可能以Hor1的方式吸附在表面层Ni原子的顶位,此时氢分子跟表面的距离( )和氢分子的键长( )分别为1.6286Å和0.9174Å. 在分子吸附的基础上计算了氢分子沿着选取的反应路径分解时的反应势垒,发现要使氢分子分解需要0.2778eV的活化能,而氢分子分解时的吸附能为0.8390eV,分解后两个氢原子的距离为3.1712Å. 在分子吸附和分解吸附时氢原子跟正下方的Ni原子都有较强的相互作用,氢原子所得到的电子主要来自氢分子正下方的Ni原子.     

含锰钢表面氢原子/氢分子吸附行为的第一性原理研究

采用基于密度泛函理论的第一性原理方法研究了氢原子和氢分子在纯铁表面和锰原子掺杂表面的吸附与解离行为.研究结果表明,氢原子可在纯铁(001)表面稳定吸附,吸附能按照顶位,桥位和心位依次增强;而溶质原子锰降低了氢原子距离表面的位置并强化了氢原子的吸附行为.氢分子在纯铁表面的吸附解离行为取决于氢分子距离模型表面的初始距离和初始空间构型.氢分子平行于纯铁(001)表面时,距离心位1.2?发生解离,而桥位、顶位均不会发生解离;氢分子垂直放置时,距离桥位0.6?、顶位1.0?发生解离,心位不会发生解离.氢分子平行于锰掺杂纯铁(001)表面时,距离桥位0.6?、顶位0.7?、心位1.2?发生解离;氢分子垂直放置时,距离桥位、心位0.8?发生解离,而顶位放置氢分子不发生解离.归纳可知,锰溶质原子掺杂会增加铁基体表面氢原子和氢分子的吸附作用并促进氢分子发生分解.     

间-吡啶基紫外光化学中的氢原子解离通道

利用高里德堡态氢原子飞行时间探测技术, 在224～248 nm激发波长研究了间-吡啶基紫外光化学中的氢原子解离通道的动力学过程．氢原子光解碎片产率谱显示在234 nm附近有较宽的吸收．产物的平动能释放较小;在224～248 nm激发波长区间平均< f_T>是0.12～0.19．产物的平动能分布显示产物是H+HC≡C-CH=CH-C≡N,H 3,4-吡啶和H 2,3-吡啶,以H HC≡C-CH=CH-C≡N为主要的氢原子生成通道．氢原子碎片具有各向同性的角度分布．研究结果表明,在紫外电子态激发以后,间-吡啶基经过内转换到电子基态,再经由单分子解离到H HC≡C-CH=CH-C≡N,H 3,4-吡啶和H 2,3-吡啶产物．间-吡啶基的紫外光解机理和以前报道过的邻-吡啶基的紫外光解机理相似．     

氢原子的X射线新谱系的实验观测及其解释

 引出氢（氘）气放电产生的射线和粒子流打在非晶聚氘乙烯C₂D₄和有机玻璃C₅H₈O₂等靶上,测得其散射谱上有多条尖锐的X谱线,其中除一条外都是（不经散射的）原始谱中没有的。经反复证认,这些谱线不是靶中元素（如C或O）和可能包含的杂质元素的特征X射线,也不是原始谱中X射线的衍射线,更不可能是低能电子的轫致辐射经吸收后形成的峰,认为该谱线很可能是前所未知的一类新的原子态的X射线新谱系的一部分。用曾提出的一个“小氢原子”理论模型予以解释,即认为氢（氘）气放电中产生了“小氢原子”,其（在基态）电子轨道半径约为普通氢原子的玻尔半径的1/274,该小氢原子能级之间的跃迁能够很好地解释所测到的X射线新谱系。     

Solute-solute correlations in aqueous solutions of tetramethylammonium chloride

Neutron diffraction with hydrogen/deuterium isotope substitution on the methyl group hydrogen atoms of the solute is used to investigate the distribution of the tetramethylammonium (TMA) ion, (CH₃)₄N⁺, in aqueous solution of 4·0 molal tetramethylammonium chloride at room temperature. The centre-centre correlation function for TMA ions is calculated from the HH correlation function for the solute by deconvolution of a spherical form factor representing the distribution of methyl hydrogen atoms. The centre-centre function shows a broad distribution of TMA … TMA distances, but indicates that close contacts occur frequently. This suggests that the charge interaction of TMA is not important in determining the distribution and that the TMA ion behaves more like an apolar solute.     

金刚石表面无定形碳氢薄膜生长的分子动力学模拟

利用分子动力学模拟方法研究了CH₂基团轰击金刚石(111)面所形成的无定形碳氢薄膜(a-C:H)的生长过程. 结构分析表明, 得到的无定形碳氢薄膜中碳原子的局域结构(如C–C第一近邻数)与其中氢原子的含量密切相关. CH₂ 基团入射能量的增加会导致得到的薄膜的氢含量降低, 从而改变薄膜中类sp³成键碳原子的比例.     

Spatial and speed distributions of H2 and D2 desorbed from a polycrystalline nickel surface

The desorption of hydrogen (H₂ and D₂) from a polycrystalline nickel surface has been investigated by measuring the spatial and speed distributions of the desorbed molecules. The Ni specimen was constructed as a membrane with one side exposed to hydrogen at ~ 1 atm pressure and the other side exposed to vacuum, thereby enabling us to supply hydrogen to the test surface via permeation of atoms through the membrane. These atoms recombine on the surface to form molecules that desorb into the evacuated chamber. The spatial distribution of the desorbed molecules was measured with a rotatable ionization gauge, whereas the speed distribution of molecules desorbed along the surface normal was determined by means of a time-of-flight detector in a second apparatus.     

Dynamical and structural properties of adsorbed water molecules at the TiO2 rutile-(110) surface: interfacial hydrogen bonding probed by ab-initio molecular dynamics

ABSTRACT

Ab-initio molecular dynamics (AIMD) simulations have been carried out to study a range of different and energetically-accessible adsorbed-water configurations and motifs for their vibrational and structural characteristics, in contact with rutile-(110) interfaces at 100?K. The radial pair distribution function between the titanium atoms at the interface and the hydrogen and oxygen atoms in the water monolayer show an orientation of the water molecules parallel to the surface of titania, and with hydrogen atoms pointed in the opposite direction to the surface. In some cases, a distinctive vibrational frequency region between 2500 and 3000?cm^?1 has also been observed, due to a strong dispersion interaction between water molecules. This behaviour is also seen in experimental studies of thin-film water coverage on TiO₂ surfaces.     

Studies on the structures and interactions of glutathione in aqueous solution by molecular dynamics simulations and NMR spectroscopy

All-atom molecular simulations and temperature-dependent NMR have been used to investigate the conformations and hydrogen bonds of glutathione (GSH) in aqueous solution. The simulations start from three different initial conformations. The properties are characterized by intramolecular distances, radius of gyration, root-mean-square deviation, and solvent-accessible surface. GSH is highly flexible in aqueous solutions in the simulations. Moreover, conformations can covert between “extended” and “folded” states. Interestingly, the two different hydrogen atoms in cysteine (H_N2) and glycin (H_N3) show different capabilities in forming NH?OW hydrogen bonds. The temperature-dependent NMR results of the different amide hydrogen atoms also show agreements with the MD simulations. Competing formation of GSH hydrogen-bonding interactions in aqueous solutions leads to hydrogen-bonding networks and the distribution of conformations. These changes will affect the activity of GSH under physiological conditions.     

Comparative study of rare gas-H<Subscript>2</Subscript> triatomic complexes

This paper presents a comparative analysis of complexes made of one rare gas (Rg) atom and molecular hydrogen, for five different Rg atoms. In particular, the vibrational band origins have been calculated, as well as the structural properties of the associated wavefunctions. The study is extended to ultra-cold Rg–H₂ collisions, object of a recent experiment aimed at producing ultra-cold H₂ [1]. The molecular systems are studied variationally using a simple, yet effective, isotropic trial wavefunction. A large number of potential energy surfaces available from the literature is considered. A comparative analysis shows that differences of up to two orders of magnitude exist for the zero-energy elastic cross sections of the five complexes. Corrections to the isotropic model have also been considered, showing no significant effect.     

非晶态贮氢材料锆镍合金的结构研究

本文报道了非晶态贮氢合金在吸氢前、后两种情况下作X射线散射分析得到的结果。根据对实验得到的径向分布函数RDF(r),简约径向分布函数G(r)的分析,表明吸氢后氢原子主要进入单一由锆原子组成的四面体间隙中,少部分进入由一个镍原子、三个锆原子组成的四面体间隙中;非晶态Ni_0.243Zr_0.757合金的平均配位数为10.6,内部原子配位情况在吸氢前后没有改变;样品在约20?范围内具有短程有序结构。 关键词：     

ZrMn2（110）表面结构及吸氢机理的第一性原理研究

采用基于密度泛函理论(DFT)的平面波赝势(PW-PP)方法,研究了ZrMn2（110）清洁表面结构和氢原子在表面的吸附。弛豫表面结构的计算结果表明表面结构的最表层为曲面,且表面结构的原子间隙变小。由1Zr2Mn原子组成的空位是氢原子吸附在ZrMn2（110）表面的最佳吸附位,吸附能为3.352 eV,氢原子吸附后离表面的距离为1.140 Å。Mulliken电荷布居分析表明吸附的氢原子与表面原子的相互作用主要是接近氢原子的第一层原子与氢原子的相互作用。过渡态计算表明被吸附的氢原子进入表面内部需克服的最大势垒为1.033 eV。     

Hydrogen bond dynamics in dodecanoic acid studied by QNS and NMR

The dynamics of hydrogen atoms in the hydrogen bonds of molecular dimers in dodecanoic acid (c phase) have been studied by quasi-elastic neutron scattering and pulsed nuclear magnetic resonance. Q-dependence measurements of the intensity of the quasi-elastic peak have established that the hydrogen atoms move along a line connecting the two oxygen atoms in the hydrogen bond. The correlation time for this motion has been studied by temperature dependence measurements of the width of the quasi-elastic line and of the proton spin-lattice relaxation time,T ₁. These studies reveal the quantum mechanical nature of the dynamics in the low temperature region. The dynamical parameters which characterise the motion have been determined by fitting the data to a model which invokes phonon assisted tunnelling. The frequency dependence ofT ₁ at low temperature is anomalous because the gradient of the ln(T ₁) vs 1/T curve is dependent on the applied magnetic field.