CH3OH在ZnO(0001)表面的光催化解离

本文利用266 nm波长的激光及程序升温脱附的方法研究了甲醇在ZnO(0001)表面的光催化反应. TPD结果显示部分的CH₃OH以分子的形式吸附在ZnO(0001)表面,而另外一部分在表面发生了解离. 实验过程中探测到H₂,CH₃^·,H₂O,CO,CH₂O,CO₂和CH₃OH这些热反应产物. 紫外激光照射实验结果表明光照可以促进CH₃OH/CH₃O^·解离形成CH₂O,在程序升温或光照的过程中它又可以转变为HCOO^-. CH₂OH_Zn与OH_ad反应在Zn位点上形成H₂O分子. 升温或光照都能促进CH₃O^·转变为CH₃^·. 该研究对CH₃OH在ZnO(0001)表面的光催化反应机理提供了一个新的见解.     

基于从头算势能面对S-(2P)+H2(1Σ+g)→SH-(1Σ)+H(2S)反应的量子含时波包计算

本文基于离子分子SH₂^-基态势能面,应用含时波包方法研究了反应S^-(²P)+H₂(¹Σ⁺_g)→SH^-(¹Σ)+H(²S)的动力学行为. 给出了反应几率和积分截面随碰撞能的变化关系,结果表明,在讨论的所有碰撞能量范围内二者均存在显著的振荡结构. 当初始转动量子数j=0,2,4,6,8,10和振动量子数v=0,1,2,3,4时,从总反应几率数值计算中可以看出,双原子H₂的振动激发和转动激发显著提高了反应活性. 同时积分散射截面的理论值与前人的实验值相符合.     

AgO分子C2∏-X2∏(0,0)带高分辨光谱再研究

本文利用激光诱导荧光技术对AgO分子C²∏-X²∏(0,0)带光谱在∽0.02 cm^-1分辨率水平开展了高分辨研究. 在超声射流条件下利用银针电极对O₂/Ar混合气高压放电制备AgO分子，利用自行研制的窄线宽单纵模光参量振荡器作为可调谐激光光源，实验记录了同位素分辨的¹⁰⁷Ag¹⁶O和¹⁰⁹Ag¹⁶O分子C²∏-X²∏(0,0)带的高分辨光谱. 通过对实验光谱的转动分析获得了两个同位素分子的精确光谱常数，其中¹⁰⁷Ag¹⁶O分子C²∏态常数为首次实验测定. 结合文献和理论计算，实验观测的C²∏态自旋-轨道耦合效应很可能来自于与四重解离态⁴Σ^-或⁴∏的态混合.     

AuCn-/0 (n=3-8)的负离子光电能谱和密度泛函理论研究：电子结合能和几何结构的奇偶效应

本文测量了AuC_n^- (n=3-8)的光电子能谱,并且对AuC_n^-/0 (n=3-8)的结构和性质进行了理论研究. 研究发现,AuC_n^-的光电子能谱表现出明显的奇偶交替变化,AuC₃^-、AuC₅^-、AuC₇^-的光电子能谱峰明显宽于AuC₄^-、AuC₆^-、AuC₈^-的光电子能谱峰,AuC₃^-、AuC₅^-、AuC₇^-的电子垂直脱附能低于AuC₄^-、AuC₆^-、AuC₈^-的电子垂直脱附能. AuC_n^- (n=3-8)的最稳定结构是链状结构. 在中性团簇AuC_n(n=3-8)中,除了AuC$₃和AuC₅的结构轻微弯曲外,其他团簇均是直线型结构. 理论计算的∠AuCC角度,Au-C键长和Au原子的电荷分布均呈现奇偶变化,与实验观测一致.     

OCS经由F 31Π里德堡态生成CO(X1Σ+)+S(1D2)产物的波长相关性光解离

本文利用时间切片离子速度成像技术在134∽140 nm波段研究了OCS分子经由F 3¹Π里德堡态的真空紫外光解离动力学. 在选取的5个分别对应OCS(F 3¹Π, v₁=0∽4)的伸缩振动激发的光解波长，实验测得了来自CO(X¹Σ⁺)+S(¹D₂)产物通道的SS(¹D₂))实验影像，并获得了总平动能谱和CO(X¹Σ⁺, v)共生产物的振动布居及角分布. 结果分析表明OCS分子解离生成CO(X¹Σ⁺)+S(¹D₂)产物的过程经历了上态F 3¹Π 与C_?v和C_s构型的下电子态间非绝热耦合过程. 实验结果显示了很强的波长相关性：OCS (F 3¹Π, v₁)的较低转动激发态(v₁=0∽2)和较高转动激发态(v₁=3, 4)的CO(X¹Σ⁺)产物的振动布居和角分布具有显著差异，表明该解离过程中具有不同的解离机理. 本结果提供了振动耦合可能对真空紫外光解离动力学产生关键作用的相关证据.     

Ti+(CO2)2Ar和Ti+(CO2)n(n=3-7)络合物离子的红外光解离光谱 (cited: 1)

利用脉冲激光溅射-超声分子束载带方法制备了气相Ti⁺(CO₂)₂Ar和Ti⁺(CO₂)_n(n=3-7)络合物离子．采用红外光解离光谱研究了这些选定的质量离子的振动光谱． 对于每一种络合物离子, 在CO伸缩振动频率范围都观察到了振动峰,表明这些离子具有插入的OTi⁺CO(CO₂)_n-1结构． 对于n≦5的OTi⁺CO(CO₂)_n-1离子,其CO振动和CO₂的反对称伸缩振动频率都比自由的CO和CO₂的频率要高,表明CO和CO₂配体与中心金属离子之间主要是静电相互作用．实验结果还表明TiO⁺可以直接络合五个配体(1个CO和4个CO₂分子)．对于n=2络合物体系,除了插入的OTi⁺CO(CO₂)结构以外,还观察到了具有弯曲结构的OCO-Ti⁺-OCO异构体的存在     

氮分子离子A2Πu-X2Σ+g 带系转动光谱分析:

利用光外差速度调制分子光谱技术测得氮分子离子A²Π_u-X²Σ⁺_g 带系的(3,1)、(4,2)、(5,3)、(8,5)带的谱线,其中(5,3)带是第一次被指认．利用测得的4个带以及文献中的14个带的谱线进行全局拟合,得到了一系列的分子常数(υ_A=0～9和υ_A=0～5)．     

He2分子 b3Πg(v=9)态的预解离

利用光外差-浓度调制吸收光谱技术测量了b³Π_g～a³∑_u⁺(9,3)带在12065～12445 cm^-1的光谱,并研究了He₂分子b³Π_g(v=9)态与c³∑_g⁺ 态的预解离相互作用．基于He₂分子c³∑_g⁺ 态的ab initio理论计算势能曲线和b³Π_g态的RKR势能曲线,分析了b³Π_g(v=9)态的预解离机制,并计算了b³Π_g(v=9)态转动能级的预解离线宽,计算结果同实验测量基本一致.     

AlnC4-/0(n=2∽4)团簇的结构和成键性质: 光电子能谱和理论计算

本文采用尺寸选择的负离子光电子能谱与高精度理论计算,对Al_nC₄^-/0(n=2∽4))团簇的结构和成键性质进行了研究. Al₂C₄^-团簇负离子的最稳定结构是一个C_2v对称的平面结构,其中两个C₂单元与两个铝原子分别相连. Al₂C₄^-团簇负离子的次稳定结构是一个线型结构,两个铝原子位于C₄线型结构两端,能量仅比最稳定结构高0.05 eV. 中性Al₂C₄团簇是一个线型结构. Al₃C₄^-团簇负离子是一个平面结构,其中三个铝原子分别与两个C₂单元相连. 而中性Al₃C₄团簇则是一个V字型结构. Al₄C₄^-团簇负离子和中性Al₄C₄团簇均为C_2h对称的平面结构,四个铝原子分别位于两个C₂单元的末端. Al_nC₄^-/0(n=2∽4))团簇负离子的自适应自然密度配分的分析结果表明这些团簇中铝原子与C₂单元之间的化学键具有σ和π键特征.     

Preparation and Characterization of Storage and Emission Functional Material of Chlorine Anion: [Ca24Al28O64]4+·(Cl-)3.80(O2-)0.10

通过碳酸钙、γ-三氧化二铝、氯化钙在氯气/氩气混合气气氛下的固态反应制备了一种氯负离子存储-发射功能材料[Ca₂₄Al₂₈O₆₄]⁴⁺·(Cl^-)_3.80(O^2-)_0.10(C12A7-Cl^-)．通过离子色谱、电子顺磁共振、拉曼光谱验证,C12A7-Cl^-材料中存储的负离子主要是氯负离子,浓度为(2.21±0.24)×10²¹ cm^-3,此外还有小部分的氧二价负离子、氧负离子、氧分子负离子．这与通过飞行时间质谱得到的结果一致：从C12A7-Cl^-材料表面发射出的负离子主要是氯负离子(大约90%),还有小部分的氧负离子和电子．材料结构和表观变化分别由X射线衍射和场发射扫描电子显微镜表征     

Size-dependent microstructure and europium site preference influence fluorescent properties of Eu-doped Ca10(PO4)6(OH)2 nanocrystal

In this study, Eu³⁺-doped nanocrystalline Ca₁₀(PO₄)₆(OH)₂ (Ca_10−xEu_x(PO₄)₆(OH)₂) with different particle sizes have been prepared by the thermal decomposition of precursors. Size-dependent microstructure could be observed in nanocrystalline Ca_10−xEu_x(PO₄)₆(OH)₂. The lattices of Ca_10−xEu_x(PO₄)₆(OH)₂ nanocrystals were more distorted in comparison with the bulk, and the smaller the particle size, the more distorted the lattices. Room temperature photoluminescence showed europium site preference was also size-dependent, with the majority of Eu³⁺ ions occupying Ca(II) sites in the bulk, but more and more Eu³⁺ ions occupying Ca(I) sites in Ca_10−xEu_x(PO₄)₆(OH)₂ with decreasing particle size. Fluorescent properties of Ca_10−xEu_x(PO₄)₆(OH)₂ were considered to be influenced by both microstructure and site preference of Eu³⁺ ions. An abnormal strong intensity of ⁵D₀-⁷F₀ transition was observed in bulk and larger Ca_10−xEu_x(PO₄)₆(OH)₂ nanocrystals, but the relative intensities of ⁵D₀-⁷F₀ transition to ⁵D₀-⁷F_1,2,3,4 transition of Eu³⁺ became weaker as the particle sizes decreased. As the particle sizes became smaller, the ratios of the red emission transition (⁵D₀-⁷F₂) to the orange emission transition (⁵D₀-⁷F₁) (R/O values) first increased by comparing the bulk sample with 96 nm sample, and then decreased by comparing 96 nm sample to 57 nm sample. The quenching concentrations of Ca_10−xEu_x(PO₄)₆(OH)₂ samples increased with decreasing particle size. Possible mechanisms responsible for these phenomena were proposed. Since nanosized Ca_10−xEu_x(PO₄)₆(OH)₂ showed higher fluorescent intensities, higher R/O values and higher quenching concentrations, this material is considered to be a promising phosphor.     

Vibrational properties of superionic glasses (AgI)x(Ag2O nB2O3)1-x

In this letter we refer on the Raman-scattering measurements in superionic glasses (AgI)_x(Ag₂O nB₂O₃)_1-x where 0 ? x ? 0.5. The behaviour of the low-frequency Raman spectra, Δν < 250 cm^?1, has been interpreted as due to a vibrational density of states mainly due to the silver halide. Nonlinear increase of the Raman efficiency with the increase of AgI concentration has been found: a phenomenological explanation is presented.     

Contribution to the study of the 2ν5 (A1) rovibrational band of CH3Br near 2860 cm−1

This band was studied on a Fourier Transform spectrum (resolving power of the apparatus: 0.005 cm^?1). For each isotopic species CH₃⁷⁹Br and CH₃⁸¹Br, about 800 lines were assigned. The band is well explained by a x-y type Coriolis interaction with ν₂ + ν₅. Several local resonances occur for low K values as well as a doubling of the K = 3 levels. Their study provides interesting information on neighboring bands, especially 3ν₆(E), ν₂ + ν₃ + ν₆, and 2ν₅(E).     

Spin dynamics in the impurity-doped one-dimensional heisenberg paramagnet (CH3)4NMn(1-x)CuXCl3: Nuclear magnetic relaxation

Proton spin-lattice relaxation rate has been measured at room temperature in the impurity-doped (CH₃)₄NMn_(1-x)Cu_xCl₃ for X = 0.04, 0.1 and 0.17. The result for Hz. snfc;chain-axis as a function of resonance frequency clearly shows that the spectral density of the spin fluctuations in the impure system remains to have the characteristics 1-D diffusive term (ω^{-$\text{1}\text{2}$}), with a slower rate of the spin diffusion in accordance with the theory by Richards. The result for H⊥ chain-axis indicates, however, the existence of a singularity of the fluctuations near ω = 0.     

The effect of the next nearest neighbor ion on the X-ray photoelectron spectra of 2p levels for Co2+, Ni2+ and Cu2+ in MgO

The X-ray photoelectron spectra of Co, Ni and Cu 2p levels for samples of M_xMg_1-xO (M = Co, Ni, Cu), CoO, NiO and CuO were compared. The binding energies of metal 2p_{$\text{3}\text{2}$} levels did not change with their concentration. The shake-up satellite main peak intensity ratios and FWHM of metal 2p levels for Co²⁺ and Cu²⁺ in MgO were smaller than those for CoO and CuO. The Ni 2p_{$\text{3}\text{2}$} spectrum for Ni²⁺ in MgO had no shoulder, unlike NiO. Results indicate that next nearest neighbor ions (metal ions) may influence the final states after photoelectron ejection.     

Thermoelectric power of the vitreous electrolyte (AgI)0.79(Ag2O.B2O3)0.21

We have determined the thermoelectric power ? of the high ionic conductivity glass (AgI)_0.79(Ag₂O.B₂O₃)_0.21; ? is negative throughout the investigated T range, 320–500 K. The heat of transport of the mobile Ag⁺, Q_Ag, taken as the slope of the straight line fitting ? versus 1/T, is quite lower than the activation energy obtained from conductivity data, viz. Q_Ag = 2.81 kcal/mole^-1 < E_act = 4.34 kcalmole^-1. To circumvent this discrepancy, the analysis of the experimental data is carried out as follows: (i) it is supposed that Q_Ag = E_act in agreement with the free ion theory for solid electrolytes; (ii) the vibrational part of the silver ion entropy, S(Ag⁺, vib), is assumed to be equal to the entropy of silver, S(Ag); (iii) on the ground of a structural model for this kind of glasses, the ideal configurational entropy of the mobile Ag⁺, S(Ag⁺, conf)_id, is evaluated through a statistical approach. The ideal ionic entropy is defined as S(Ag⁺)_id = {S(Ag⁺, vib) + S(Ag⁺, conf)_id}; (iv) the difference {S(Ag⁺)_exp - S(Ag⁺)_id} is viewed as an excess entropy and is described according to the classical model of the regular solutions.     

(CH3I)n(n=1,2,3,4)的同步辐射光电离研究

用VUV同步辐射辐照在连续的超声射流冷却束中产生的（CH₃I)_n（n=1,2，3，4）团簇分子，通过测量其光电离及解离电离产生的各种离子的光电离效率（PIE）曲线，获得了（CH₃I)_n⁺（n=1，2，3，4）的绝热电离势及各种碎片离子的出现势，估算了有关分子的键能．在CH₃I⁺的PIＥ曲线上观察到CH₃I分子的自电离结构，并对其进行了标识，归属为收敛于CH₃I⁺（²E_1/2）态的4组Rydberg系，即ns，npσ，npπ和nd． 关键词：     

三甲基镓在Pd(111)表面吸附解离及表面预吸附H和O的影响

利用X-射线光电子能谱（XPS）和程序升温脱附谱（TPD）研究了三甲基镓在Pd（111）表面的吸附和解离行为,并考察了表面预吸附H和O的影响。结果表明,在吸附温度为140 K时,三甲基镓在Pd（111）上主要为解离吸附,此时表面物种为Ga（CH₃）_x （x=1,2,3）和CH_x物种。加热将导致Ga的甲基化合物中的Ga-C键发生分步断裂,在不同温度下产生CH₄和H₂从表面脱附。同时,XPS结果证实了在275~325 K的温度区间内存在Ga甲基化合物的分子脱附。退火至更高温度,表面只观察到积碳和金属Ga物种,这二者随着温度的继续升高逐渐向体相扩散。在Pd（111）表面预吸附O和H对上述吸附和解离行为存在显著的影响。当表面预吸附H时,脱附产物CH₄和H₂的脱附主要位于315 K,可归属为一甲基镓的解离脱附。当表面预吸附O时,只在258 K观察到CH₄和H₂的脱附峰,可能来自于Pd-O-Ga（CH₃）₂吸附结构的解离.     

快离子导体AgxTiS2中Ag+离子－空位的二维基态结构与能量性质研究

根据Ag⁺离子-空位的二维有序结构建立了三维晶胞模型.采用局域密度近似下的平面波赝势方法,对有序Ag_xTiS₂(x=0,1/4,1/3,1/2,2/3,3/4,1)系列进行了几何结构优化和总能量计算,并与Li_xTiS₂系列进行了对比研究.有序Ag_xTiS₂系统的晶格参量增量Δa_{关键词： x}TiS₂')" href="#">Ag_xTiS₂ 有序—无序相变 离子扩散 第一性原理计算