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1.
黄青锋  傅荣堂  孙鑫  傅柔励 《物理学报》1994,43(11):1833-1839
本文采用扩展的Hubbard模型,在电子-晶格耦合的紧束缚近似下,研究了光激发下的C60,分子的激子态和极化子态。我们发现,电子关联效应相当敏感地影响到单态和三态激子的束缚能。同时,C60分子动力学晶格弛豫使激子极化子得以形成。光激发下的C60分子,在电子相互作用U~5.0eV,V~2.0eV时,能够定性地解释荧光发射谱。 关键词:  相似文献   

2.
用532.0nm的脉冲Nd:YAG激光作为泵浦光,747.0nm的连续半导体激光作为探测光,在C60甲苯溶液中,利用C60分子的三重态-三重态非线性吸收效应,获得C60分子的全光开关和全光调制特性,并用速率方程进行了动力学数值模拟,得到与实验相一致的结果。 关键词:  相似文献   

3.
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。 关键词:  相似文献   

4.
白景旭  韩小萱  白素英  焦月春  赵建明  贾锁堂 《物理学报》2018,67(23):233201-233201
本文主要从理论和实验上研究超冷铯(60D5/22 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(60D5/22 Rydberg分子的绝热势能曲线,获得了(60D5/22 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(60D5/22 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(60D5/22 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   

5.
王强华  冯玉英  杨松舲  陈凌孚 《物理学报》1994,43(10):1576-1579
测量了CCl4,CH2Cl2和CHCl3对生物膜中磷脂酰胆碱作用的紫外电子吸收光谱,实验结果表明,由于CCl4,CH2Cl2和CHCl3分子结构的差异,三种溶剂的极性依次递增,磷脂酰胆碱π-π*电子跃迁的吸收峰红移。磷脂酰胆碱在CCl4中光谱呈单吸收峰,在CH2Cl2和CHCl3中光谱特征呈双蜂结构,存在聚集体的激子态跃迁,由此给出了脂质分子聚集状态的光谱依据。 关键词:  相似文献   

6.
石磊  黄云松  周贵恩  张裕恒 《物理学报》1996,45(12):1986-1991
根据X射线衍射基本理论,计算了C60分子晶体中的各种堆积方式下的X射线衍射花样,对C60分子晶体中的类非晶散射产生的原因进行了探讨,指出在C60分子晶体中,C60分子有两种运动方式.非晶散射是C60分子晶体固有结构特征所造成的 关键词:  相似文献   

7.
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(22),B(21),C(21)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+(X22)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+(X22,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 关键词:  相似文献   

8.
用非弹性中子散射实验方法研究了非晶态Fe90-xCoZr10(x=10,40)和Fe80-yCr13(y=4,8)合金的广义声子谱,在低能区域(?ω≤20meV)观察到了与因瓦效应相关的声子谱软化现象。初步讨论了这种动力学方面的反常行为。结果表明,声子谱软化可能与在因瓦合金中存在增强的电子-声子相互作用有关。 关键词:  相似文献   

9.
方泉玉  蔡蔚  沈智军  邹宇  李萍  徐元光 《物理学报》1996,45(10):1641-1646
用自编的扭曲波程序ACDW(9)和拟合程序FIT(9),计算了一系列类锂离子的碰撞激发过程.找出了约化碰撞强度Ωred是约化电子能量εred的慢变函数,约化速率系数因子γred是约化电子温度Tred的慢变函数.对某种离子的一个激发过程,可用10个参数描述,由这10个参数可以得到任意电子能量下的碰撞强度和激发截面,以及任意温度下的速率系数 关键词:  相似文献   

10.
于威  李晓苇  韩理  张连水  傅广生 《物理学报》1994,43(11):1889-1898
采用光学发射谱(OES)技术对脉冲TEA CO2激光诱发SiH4+CH4系统击穿产生的等离子体辐射进行了时间分辨的光谱测量。结果表明等离子体内分子的各碎片发光均在气体击穿时刻开始出现,但具有不同的时间特性,由此探讨了气体分子的分解过程。分析结果支持激光诱发SiH4+CH4等离子体内的主要离解通道为产生Si,C原子通道的分解动力学机制的解释。据此观点讨论了气体分解碎片间的反应过程。实验与理论符合较好。 关键词:  相似文献   

11.
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   

12.
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   

13.
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   

14.
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   

15.
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   

16.
《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   

17.
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   

18.
王晓雄  李宏年 《物理学报》2006,55(8):4259-4264
用X射线光电子能谱研究了Sm掺杂的固态C60相衍变和芯电子态.在SmxC60中Sm的含量x小于0.5时,样品是固溶相;在x=0.5和x=2.75之间的掺杂阶段,样品是这两个相的混合.在x=2.75和x=6之间的高掺杂阶段未观察到相分离的X射线光电子能谱证据.Sm 4f, 4d的实验数据表明Sm的价态是+2.二价Sm 3d5/2芯态谱线存在两个子峰. 关键词: 60的Sm填隙化合物')" href="#">C60的Sm填隙化合物 相结构 电子态 X射线光电子能谱  相似文献   

19.
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   

20.
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   

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