磁瓶式光电子能谱和速度成像光电子能谱对APS~-(A=C_(14)H_(10),蒽)的研究:电子结构,APS~?的自旋轨道耦合和APS~-的自旋偶极态（英文）

Dibenzo-7-phosphanorbornadiene P-sulfide anions APS-(A=C_(14)H_(10),蒽)是一种非常重要有机磷分子前驱体.该类化合物通过释放有机成分蒽,进而得到纯净的各种无机磷小分子.本文通过电喷雾离子技术将其从溶液相转移到气相中,然后通过磁瓶式光电子飞行时间能谱和速度成像光电子能谱,并结合计算对其几何和电子结构进行研究.通过不同波长的光谱对比以及Franck-Condon模拟,得到其电子亲和势(2.62±0.05 eV)和自旋轨道劈裂(43±7 meV).实验光谱不仅给出丰富的电子结构信息,而且呈现一个非常独特的现象:不同波长(440、450、460 nm)的速度成像光电子能谱在同一位置均出现一个尖锐的峰.理论计算显示APS有足够大偶极矩(3.31 D),能够产生自旋偶极电子.进一步的计算将具有相同动能(17.9 meV)的强峰归属来自振动-电子态耦合引起的电子自动脱附的态-态跃迁过程.通过对其几何结构和电子结构的研究,有助于理解磷转移反应中化学键的断裂和形成.     

50—5000 eV电子被C4H8O,C5H10O2, C6H5CH3和C4H8O2散射的总截面

使用电子被C, H和O原子散射总截面的实验数据, 利用修正后的可加性规则计算了能量为50—5000eV的电子被4个复杂大分子C₄H₈O, C₅H₁₀O₂, C₆H₅CH₃和C₄H₈O₂散射的总截面, 并将计算结果与实验结果及其他理论计算结果进行了比较. 结果表明, 即 关键词： 电子散射 可加性规则 总截面 几何屏蔽效应     

基于Gelius模型计算的C60和C70的紫外光电子能谱

在B3LYP/6-31G(d,p)水平上对两种富勒烯C₆₀和C₇₀进行了构型优化. 在此基础上,并基于Gelius模型, 计算了这两种富勒烯的紫外光电子能谱曲线. 理论计算的曲线同实验曲线符合的很好.此外, 从理论曲线并结合量子化学计算的结果, 可以看到, C₇₀分子上不同化学环境的的碳原子对紫外光电子能谱曲线的贡献是不同的.     

C2和C2+,C2-的电子结构与势形共振

本文在独立电子近似的基础上,根据多重散射自洽场理论方法,计算了C₂和C₂⁺,C₂^-分子(离子)的电子结构,阐明了势形共振能量和上述分子(离子)电子数的关系,结果表明,随着电子数的减少,C原子2s-2p轨道杂化减弱,势形共振的能量将降低(如降低到阈值下,则势形共振消失)。 关键词：     

C80H80几何结构和电子性质的密度泛函研究

采用密度泛函理论方法中的广义梯度近似,对C₈₀H₈₀几何结构和电子性质进行了研究. 几何结构研究表明:在C₈₀H₈₀可能稳定存在的两种同分异构体中, 连接12个五边形的20个C原子内部氢化,其余60个C原子外部氢化所形成的结构即 H₂₀@C₈₀H₆₀最稳定,其仍然保持I_h对称性. 通过对H₂₀@C₈₀H₆₀的能级、前线轨道和态密度分析可知: 在H₂₀@C₈₀H₆₀中, H原子的原子轨道与C原子的原子轨道之间在占据态轨道上有较强的杂化, H原子对H₂₀@C₈₀H₆₀的占据态轨道的贡献比较大. 其最高占据轨道主要由外部H原子和碳笼来贡献,而最低未占据轨道主要由内部H原子贡献, 表明内外H原子在H₂₀@C₈₀H₆₀的化学反应中承担不同的角色. H₂₀@C₈₀H₆₀为闭壳层结构,所有电子都是配对的,表现为非磁性.     

124Te核1+态和高自旋态能谱特征的微观研究

利用微观sdIBM-2+2q.p.方案，成功地计算出¹²⁴Te核的低自旋态和部分高自旋态，特别是较成功地再现了1⁺₁,1⁺₂,3⁺₁，3⁺₂和5⁺₁态.基于该方案推出的能量关系指认：6⁺₁，8⁺_{关键词： 能谱特征 拆对与顺排 微观sdIBM-2+2q.p.方案 124Te核')" href="#">¹²⁴Te核}     

光电子成像研究AgOCH3-和Ag-(CH3OH)x (x=1, 2)

用光电子成像技术和从头算法研究Ag^-(CH₃OH)_x (x=1, 2)和AgOCH₃^-. 从AgOCH₃^-振动分辨的光电子谱得 到AgOCH₃^-的绝热和垂直电离能分别为1.29(2)和1.34(2) eV. Ag^-(CH₃OH)_{1,2相似文献}   

C72,La2@C72几何结构和电子性质的计算研究

采用密度泛涵理论(density functional theory, DFT)中的广义梯度近似(generally gradient approximation, GGA)对富勒烯C₇₂和内掺金属La富勒烯La₂@C₇₂三种同分异构体的几何结构和电子结构进行研究.发现在C₇₂的三种同分异构体中，满足独立五边形规则(isolated-pentagon-rule，IPR)的C₇₂(D_{6d< 关键词： 72}')" href="#">C₇₂ 2@C₇₂')" href="#">La₂@C₇₂ 密度泛涵理论 几何结构 电子结构     

C2H221分子转动角动量定向分布(Orientation)及其碰撞弛豫和转移

利用圆偏振激光受激Raman抽运,以 C₂H₂分子为样品选择性地制备了它的电子基态单一转动态(X¹Σ⁺_g,ν″₂＝1,J″的角动量定向布居(orientation)．并从圆偏振紫外激光诱导的A¹A_u(ν′₃＝1)←X¹Σ⁺_g(ν″₂＝1)的荧光（谱）,直接测定了 C₂H₂(X¹Σ^＋_g,ν″₂＝1,J″＝4,7,8,…,13）的角动量定向布居值．从时间分辨的荧光信号谱测定了角动量定向布居的碰撞弛豫速率常数,同时还研究了由各初始激励的转动态向其他邻近转动态碰撞诱导的角动量定向布居转移． 关键词：     

Au2Gen-/0 (n=1∽8)团簇结构演化和电子性质的光电子能谱和理论计算研究

本文利用尺寸选择的负离子光电子能谱和理论计算探索Au₂Ge_n^-/0 (n=1∽8)团簇的结构演化和电子性质. 通过比较理论模拟谱与实验谱,并使用CCSD(T)理论方法计算异构体的相对能量,从而确定金锗混合团簇的全局最小结构. 本文发现Au₂Ge_n^-/0 (n=1∽8)团簇的两个Au原子具有较高的配位数和较弱的亲金相互作用. 负离子团簇和中性团簇的最稳定结构分别处于自旋双重态和自旋单重态. 除了Au₂Ge₄^-/0和Au₂Ge₅^-/0,负离子团簇和中性团簇的全局最小结构具有相似的结构特点. Au₂Ge₁^-/0团簇是一个C_2v对称的V形结构,而Au₂Ge₂^-/0团簇是一个C_2v对称的双桥连结构. Au₂Ge₁^-负离子团簇是两个Au原子盖帽的Ge₄四面体结构,而Au₂Ge₄中性团簇是两个Au原子盖帽的Ge₄菱形结构. Au₂Ge_5∽8^-/0团簇主要采用三棱柱、四棱柱、及五棱柱结构. Au₂Ge₆是一个C_2v对称的四棱柱结构,并表现出σ和π双键性质.     

ZrO-双原子阴离子的光电子成像谱

利用激光溅射制备了ZrO^-双原子阴离子,测量了其光电子成像谱．实验观测到的光电子能谱可以在光学光谱和高精度从头计算的基础上得到很好的归属．ZrO^-的基态确定为²△态,其自旋-轨道分裂能为578±12 cm^-1,ZrO的电子亲和能测定为1.249±0.005 eV．第一次在实验上观测到ZrO的c³∑^-激发态,其相对于X¹∑⁺基态的能量为13316±24 cm^-1,同时还对ZrO与其等电子体NbN的电子结构进行了比较．     

1-碘丙烷分子的电子动量谱学研究：自旋-轨道耦合效应与分子内轨道相互作用

利用不对称不共面电子动量谱仪,在2.5 keV碰撞能量下,采用高精度的SAC-CI方法计算了1-碘丙烷分子束缚能谱,同时采用Hartree-Fock、B3LYP/aug-cc-pVTZ(C,H)6-311G^**(I)方法计算其电子动量分布. 并对电离能峰进行了标示. 结合非相对论与相对论计算方法以及自然键轨道分析,对最外层两个轨道(碘的5p孤对)的自旋-轨道耦合效应与分子内轨道相互作用进行了比较. 两种相互作用对电子动量分布的不同影响是可观的. 实验结果与相对论计算的结果一致,表明1-碘丙烷分子内自旋-轨道耦合效应占主导.     

Electronic structure of non-centrosymmetric AgCd2GaS4 and AgCd2GaSe4 single crystals

X-ray photoelectron core-level and valence-band spectra for pristine and Ar⁺-ion irradiated (0 0 1) surfaces of AgCd₂GaS₄ and AgCd₂GaSe₄ single crystals grown, respectively, by the Bridgman method and the method of direct crystallization have been measured in the present work. The X-ray photoelectron spectroscopy (XPS) results reveal high chemical stability of (0 0 1) surfaces of AgCd₂GaS₄ and AgCd₂GaSe₄ single crystals. Electronic structure of AgCd₂GaS₄ has been calculated employing the full potential linearized augmented plane wave method. For the AgCd₂GaS₄ compound, the X-ray emission bands representing the energy distribution of the valence Ag d-, Cd d-, Ga p- and S p-like states were recorded and compared on a common energy scale with the XPS valence-band spectrum. The theoretical and experimental data regarding the occupation of the valence band of AgCd₂GaS₄ were found to be in excellent agreement to each other. Second harmonic generation (SHG) efficiency of AgCd₂GaS₄ by using the 320 ns CO laser at 5.5 μm has been recorded within the temperature range 80–300 K. Substantial increase of the photoinduced SHG which in turn is substantially dependent on the temperature has been detected for the AgCd₂GaS₄ compound.     

Gas phase electronic spectrum of propadienylidene C3H2

The rotationally resolved vibronic bands in the forbidden electronic transition of the cumulene carbene C₃H₂ have been observed in the gas phase by cavity ring down absorption spectroscopy through a supersonic planar plasma with allene as precursor. The band detected in the 16 223 cm⁻¹ region is a result of vibronic interaction and is assigned to a combination of a₁ and b₂ vibrations with a frequency around 2250 cm⁻¹. Another vibronic band near 15 810 cm⁻¹ has an unusual rotational structure because the K_a = 0-1 subband is absent. It is assigned to a combination of a₁ and b₁ vibrations, ∼1850 cm⁻¹, which borrow intensity from the near lying state due to a-type Coriolis coupling. A rotational analysis using a conventional Hamiltonian for an asymmetric top molecule yields molecular constants for the vibrational excited levels of the ùA₂ state, which were used for the determination of the geometry. The stronger transition of C₃H₂, measured in a neon matrix in the 16 161-24 802 cm⁻¹ range, was not detected. The reason for this is a short lifetime of the state, leading to line broadening.     

Pressure broadening and collisional shift of the Rb D2 absorption line by CH4, C2H6, C3H8, n-C4H10, and He

The pressure broadening and shift rates of the rubidium D2 absorption line 5²S_1/2→5²P_3/2 (780.24 nm) with CH₄, C₂H₆, C₃H₈, n-C₄H₁₀, and He were measured for pressures ≤80 Torr using high-resolution laser spectroscopy. The broadening rates γ_B for CH₄, C₂H₆, C₃H₈, n-C₄H₁₀, and He are 28.0, 28.1, 30.5, 31.3, and 20.3 (MHz/Torr), respectively. The corresponding shift rates γ_S are −8.4, −8.8, −9.7, −10.0, and 0.39 (MHz/Torr), respectively. The measured rates of Rb for the hydrocarbon buffer gas series of this study are also compared to the theoretically calculated rates of a purely attractive van der Waals difference potential. Good agreement is found to exist between measured and theoretical rates.     

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.     

Effects of potassium on the reaction pathway of C3H7 species over Mo2C/Mo (1 0 0)

The adsorption and surface reactions of propyl iodide on clean and potassium-modified Mo₂C/Mo(1 0 0) surfaces have been investigated by thermal desorption spectroscopy (TPD), X-ray photoelectron spectroscopy (XPS) and high resolution electron energy loss spectroscopy (HREELS) in the 100-1200 K temperature range. This work is strongly related to the better understanding of the catalytic effect of Mo₂C in the conversion of hydrocarbons. Potassium was found to be an effective promoter: it induced the rupture of C-I bond in the adsorbed C₃H₇I even at 100 K. The extent of C-I bond scission varied approximately linearly with the concentration of K coverage at the adsorption temperature of 100 K. As revealed by HREELS and TPD measurements the primary products of the dissociation are C₃H₇ and I. The former one was stabilized by potassium and underwent dehydrogenation and hydrogenation to give propene and propane. The desorption of both compounds is reaction-limited process. A fraction of propyl groups was converted into di-σ-bonded propene, which was stable up to ∼380 K. The coupling reaction of propyl species was also facilitated by potassium and resulted in the formation of hexane and hexene with T_p ∼ 230-250 K. Hydrogen was released with T_p = 390 K, indicative of a desorption limited process. The effect of potassium was explained by the extended electron donation to adsorbed propyl iodide in one hand, and by the direct interaction between potassium and I on the other hand. This was reflected by the shift of the desorption of potassium from the coadsorbed layer at and above 1.0 ML to higher temperature, and by the coincidal T_p values (∼700 K) of potassium and iodine. The formation of KI was also supported by the appearance of a loss feature at 650 cm⁻¹ in the HREEL spectra attributed to a phonon mode of KI.     

Electronic structure calculations and optical properties of a new organic-inorganic luminescent perovskite: (C9H19NH3)2PbI2Br2

(C₉H₁₉NH₃)₂PbI₂Br₂ compound is a new crystal belonging to the large hybrid organic-inorganic perovskites compounds family. Optical properties are investigated by optical absorption UV-visible and photoluminescence (PL) techniques. Bands to band absorption peak at 2.44 eV as well as an extremely strong yellow-green photoluminescence emission at 2.17 eV is observed at room temperature. First principle calculations based on the DFT and FLAPW methods combined with LDA approximation are performed as well. Density of state close to the gap is presented and discussed in terms of optical absorption and photoluminescence experimental results. The perfect agreement between experimental data and electronic structure calculations is highlighted.     

Coadsorption of CO and C6H6 on Co(0 0 0 1)

We have studied the influence of CO on the adsorption of benzene on the Co(0 0 0 1) surface using LEED, XPS, TDS and work function measurements. CO was found to reduce the benzene adsorption, but even at saturation CO exposure no complete blocking was observed. Thermal desorption of the coadsorbed layer featured CO and H₂ peaks indicating partial dehydrogenation of benzene and retaining of the CO bond. Ordered LEED structures were found with all coverages: Pre-adsorption of CO led to patterns already seen for pure carbon monoxide adsorption. Pre-adsorption of benzene showed the known structure of pure benzene also with small CO exposures, but higher CO exposures yielded a mixture of and patterns.     

Structure and phase transitions in chloroantimonate(V) crystals: [(C2H5)3NH]SbCl6 and [(C2H5)3NH]SbCl6·1/2[(C2H5)3NH]Cl

New triethylammonium salts: [(C₂H₅)₃NH]SbCl₆ (TCA) and [(C₂H₅)₃NH]SbCl₆·1/2[(C₂H₅)₃NH]Cl (TCAT) have been synthesized. The compounds crystallise in monoclinic symmetry: space groups P2₁/n and P2₁/c, for TCA at 293 K and TCAT at 100 K, respectively. The crystal structure of [(C₂H₅)₃NH]SbCl₆ consists of discrete ionic pairs—triethylammonium cations and hexachloroantimonate anions—linked via the bifurcated N-H?Cl hydrogen bonds. The crystal structure of [(C₂H₅)₃NH]SbCl₆·1/2[(C₂H₅)₃NH]Cl is composed of three symmetrically independent triethylammonium cations, chlorine anion and two symmetrically independent hexachloroantimonate anions. TCA undergoes a structural phase transition at 336 K (on heating) into the orthorhombic C222 space group, whereas TCAT reveals a structural phase transition at 332 K. The phase transitions are of the first order type. TCA shows a ferroelastic domain structure below 336 K. Differential scanning calorimetry, dilatometric, dielectric dispersion and Raman scattering measurements have been used to study the phase transition mechanisms in these triethylammonium salts.