共查询到20条相似文献,搜索用时 93 毫秒
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本文利用脉冲紫外激光(UV)选择激发氨分子到?1A″2电子激发态的两个最低振动能级ν′2=0和ν′2=1(ν2振动),然后检测新生态H原子的飞行谱(TOF),研究了氨分子的光碎片动力学。光谱证实了最近所测的离解能D00(H-NH2)=4.645eV;绝大多数生成的NH2(X2B1)基处于非振动激发,但是具有围绕a惯性轴的高度转动激发。通过NH3(?)的ν′2=1光离解产生的NH2(X)基具有较高的内部激发,并且显示了在N=Ka转动能级上的反转布居。
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本文主要从理论和实验上研究超冷铯(60D5/2)2 Rydberg分子的双色光缔合光谱.数值计算了铯60D5/2 Rydberg原子对态的长程电多极相互作用和(60D5/2)2 Rydberg分子的绝热势能曲线,获得了(60D5/2)2 Rydberg分子的势阱深度和平衡间距.实验上利用双色光缔合超冷铯原子的方法制备了(60D5/2)2 Rydberg分子.其中,第一色激光(pulse-A)双光子共振激发种子Rydberg原子A;第二色激光(pulse-B,失谐于分子的束缚能)共振激发第二个Rydberg原子B,原子A与B由分子势阱束缚形成超冷(60D5/2)2 Rydberg分子.由脉冲场电离探测技术获得Rydberg分子的光缔合光谱,测量的Rydberg分子的势阱深度与理论计算结果相一致. 相似文献
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报道在超声射流冷却条件下用同步辐射VUV光源研究CH2Br2的振动自电离结构.根据测量的105—123nm范围内母体离子(CH2Br2+)的光电离产率曲线,获得CH2Br2的绝热电离势为10.23±0.01eV.CH2Br2+的最低三个电子激发态,即A(2A2),B(2B1),C(2A1)分别位于10.78±0.01eV,11.20±0.01eV和11.27±0.01eV.在115.01—121.15nm范围内,观察到CH2Br2自电离峰叠加在若干台阶结构上,台阶平均宽度为716.8±40.0cm-1,对应于CH2Br2+(X2B2)中Br-C-Br反对称的伸缩振动(v9),所有的峰均归属为收敛于CH2Br2+(X2B2,v+)振动能级的ns,np和nd自电离Rydberg态.此外,对CH2Br2光解离电离产生离子型自由基CH2Br+(X)的光电离产率曲线的结构也进行了归属
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L. M. Ramaniah M. Boero 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2009,51(3):369-374
We report the first-principles Car-Parrinello molecular dynamics study of the behaviour of a single transition metal Ta atom
on fullerene C60, at different temperatures, and for both neutral and charged clusters. We seek to characterise the
motion of the lone Ta metal atom on the C60 surface, contrasting its behaviour both with that of three Ta atoms, as well as with a single alkali metal atom on the cage
surface.
Our earlier simulations on C60Ta3 had revealed that the Ta atoms on the surface of
the fullerene are affected by a rather high mobility, and that the motion of these atoms is highly correlated due to Ta-atom-Ta-atom
attraction. Earlier, experimental studies of a single metal atom (K, Rb) on the surface of a C60 molecule had led to the
inference that at room temperature the metal atom skates freely over the surface, the first direct evidence for which was presented by us in earlier first principles molecular dynamical simulations. 相似文献
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A. Tröster 《Phase Transitions》2013,86(4):753-764
The temperature dependence of the elastic constants in C60 is quite unusual in the vicinity of the order-disorder phase transition at 260 K, in sharp contrast to simple mean-field calculations. The observed deviations seem to be a combination of dynamical processes, the influence of defects and fluctuation effects. The latter are expected to be important, since the Landau free energy admits a third order term in the order parameter. We develop field theoretic perturbation theory for general models of this type. The formalism is applied to a simple scalar model of C60 and the resulting temperature dependence of elastic constants is discussed. 相似文献
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The stability of fullerenes (C60 and C70) under swift heavy ion irradiation is investigated. C60 and C70 thin films were irradiated with 120 MeV Ag ions at fluences from 1×1012 to 3×1013 ions/cm2. The damage cross-section and radius of damaged cylindrical zone were found to be higher for C60 than C70 as evaluated by Raman spectroscopy, which shows that the C70 molecule is more stable under energetic ion impact. The higher damage cross-section of the C60 molecule compared with that of the C70 molecule is explained on the basis of thermal conductivity in the framework of the thermal spike model. The surface morphology of pristine C60 and C70 films is studied by atomic force microscopy. UV-visible absorption studies revealed that band gap for C60 and C70 fullerenes thin films decreases with increasing ion fluence. Resistivity of C60 and C70 thin films decreases with increasing ion fluence but the decrease is faster for C60 than C70, indicating higher damage in C60. Irradiation at a fluence of 3×1013 ions/cm2 results in complete damage of fullerenes (C60 and C70) into amorphous carbon. 相似文献
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V. F. Masterov A. V. Prikhod’ko T. R. Stepanova V. Yu. Davydov O. I. Kon’kov 《Physics of the Solid State》1998,40(3):535-538
The crystalline structure of a C60/C70 membrane prepared by an original technique has been studied by x-ray diffraction and Raman spectroscopy. The effects of purification of the starting C60/C70 mixture to C70 composition and of spatial separation of the C60 and C70 phases in the membrane have been revealed. The samples studied were established to have a composition gradient from C60 to C70. The main structure of the membrane is shown to be an fcc lattice with a=14.308 Å. 相似文献
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Yufang WangXuewei Cao Hyon U. HanGuoxiang Lan 《Journal of Physics and Chemistry of Solids》2002,63(11):2053-2056
Samarium-fullerene intercalation compounds of nominal composition SmxC60 (x=1,2,…,6) have been synthesized by a solid-state reaction method. We obtain a Sm2.75C60 superconducting phase with orthogonal structure and a Sm6C60 phase with body-centered cubic structure. The broadening and weakening of Raman peaks of the SmxC60 compounds are due to the distortion of C60 and electron-phonon interaction. The Raman measurements reveal that the distortion of C60 decrease in SmxC60 (x=3,4,5) exposed to air, although the fulleride solids have transformed into an amorphous state. The Raman results also show that the distortion of C60 is still very large in the Sm6C60 exposed to air, or the C60 molecules have been destroyed and become some amorphous carbide. 相似文献
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《Physics letters. A》2006,360(2):294-298
The dynamical and static dipole polarizabilities of the C60 molecule have been calculated on the basis of the experimental data on the cross section of the fullerene photoabsorption. It has been shown that the fullerene shell in the static electric field behaves most likely as a set of separate carbon atoms rather than as a conducting sphere. 相似文献
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基于C60受体和有机分子给体的太阳能电池是目前非常重要的一个研究热点, 利用同步辐射真空紫外光电子能谱(SRUPS) 技术研究了酞菁铁(FePc)与TiO2(110)及C60的界面电子结构, 以及FePc与C60分子混合薄膜的电子结构. SRUPS价带谱显示, FePc沉积在化学计量比与还原态两种不同的TiO2(110)表面时, FePc分子的HOMO能级均随FePc厚度的变化发生了移动, 而在化学计量比的TiO2(110)表面位移较大, 同时发生界面能带弯曲, 说明存在从有机层向衬底的电子转移. 在FePc/C60和C60/FePc界面形成过程中, FePc与C60分子的最高占据分子轨道(HOMO)位移大小基本相同. 由界面能级排列发现, 在FePc与C60的混合薄膜中, FePc分子的HOMO与C60分子的最高占据分子轨道能级差较大, 这有利于提高器件开路电压, 改善器件性能. 相似文献
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Synchrotron-based high-resolution photoemission spectroscopy (PES) and in situ scanning tunneling microscopy (STM) are used to investigate the interaction at the C60-SiC nanomesh interface during the sequential deposition and subsequent desorption of C60 molecules. A weak charge transfer occurs at the C60-nanomesh interface, involving electrons transferring from nanomesh to C60 overlayer. The interface interaction originated from the weak charge transfer at the C60-nanomesh interface is stronger than C60 intermolecular interaction (e.g., van-der-Waals force), facilitating the layer-by-layer growth for the first two layers of C60 on SiC nanomesh. The highly corrugated nanomesh surface results in an anisotropic diffusion and high diffusion barrier of C60 on top, and thereby leads to the formation of irregularly shaped C60 islands under submonolayer condition. In contrast, C60 diffusion on HOPG and Ag(1 1 1) surfaces is rather isotropic, resulting in the formation of hexagonally shaped C60 islands with smooth domain boundaries. STM results show the partial desorption of C60 molecules from the SiC nanomesh surface after annealing the 1 ML C60 sample (complete wetting layer of C60 on SiC nanomesh) at around 150 °C for 20 min. Thorough desorption of C60 molecules and full recovery of the clean SiC nanomesh are observed after annealing at around 200 °C for 20 min. In situ PES and STM experiments clearly demonstrate that C60 adsorption and desorption processes do not affect the underlying SiC nanomesh structure, revealing its thermal stability and chemical inertness to C60 molecules. 相似文献
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Jason Sallgren Hui Wang Samantha L. Leonard Yun Hang Hu 《Journal of Physics and Chemistry of Solids》2012,73(9):1071-1074
The morphologies of deposited C60 on a copper substrate from a C60-benzene solution were evaluated by using Scanning Electron Microscopy. It was found that the forms of deposited C60 were dependent on the aggregation of C60 in its original solution. During natural vaporization of benzene solution on a copper substrate, independent C60 molecules in the solution assembled into crystal C60 on the substrate, whereas the aggregates of C60 in the solution were remained as amorphous C60 particles on the substrate. However, if spinning was employed during vaporizing solvent, the C60 aggregates were destroyed, leading to the formation of crystal C60. Furthermore, the speed of spinning a substrate can tune the size and shape of deposited C60. 相似文献