Coadsorption of Oxygen and C60 Molecules on (100)Mo Surface

Abstract

Auger-electron spectroscopy was used to study oxygen adsorption on C₆₀ molecules film on (100)Mo. It appeares that one monolayer of C₆₀ molecules does not completely protect metal substrate from oxidation, and one needs thin C₆₀ film with thickness of 2-3 ML for complete reduction of oxygen penetration to the substrate from gas phase.     

Coadsorption of aluminum and group IV (Si,C) atoms on W(100) surface

Electropositive atoms of aluminum adsorbed on a W(100) surface exhibit competition with silicon adatoms for the adsorption sites at high temperatures (1200–1500 K). In this system, silicon displaces aluminum from the tungsten surface. No such competition is observed during the coadsorption of aluminum and carbon, where adatoms of both elements coexist on the tungsten surface (in contrast to the situation previously observed on rhenium, where aluminum atoms displaced carbon to the bulk of substrate). The nature of competition in the systems studied is apparently analogous to that observed previously for Si, C, and S atoms on W(100), despite the fact that aluminum atoms (in contrast to the nonmetals) in the adsorbed state possess a positive charge.     

Au电极作用下C60、2C60与4C60富勒烯分子的电子传输特性

采用扩展的Hückel方法与格林函数方法,研究了Au电极作用下,C60富勒烯、2C60和4C60聚合体分子的电子结构与导电性,并对它们的电子结构与电子输运特性进行了对比.研究结果表明,C60、2C60或4C60富勒烯分子与Au电极 "接触"后,其HOMO、LUMO间的能隙减小;C60、2C60或4C60分子与Au电极之间的结合既有共价键的成分,又有离子键的成分,其中,C60、4C60分子与Au电极结合的离子键特征更为明显;三种富勒烯分子的电子输运性能依次具有C60>2C60>4C60分子的顺序.     

Contact stability of C60 molecules on pure and doped (100) tungsten surface

The influence of the metal surface doping on the contact stability of adsorbed fullerene molecules at room temperature was observed for the first time. The C₆₀ fullerene molecules decompose at room temperature both on a pure (100)W surface and on a tungsten surface containing carbide (WC), while the presence of a surface silicide of the same stoichiometry (WSi) produces passivation of the metal surface, thus preventing the fullerene molecules from decomposition.     

Ultra-thin zinc oxide film on Mo(100)

Zinc oxide films on a single crystal Mo(100) substrate were fabricated by annealing the pre-deposited metal Zn films in 10^− 5-10^− 4 Pa O₂ ambience at 300-525 K, and were characterized by in situ Auger electron spectroscopy, electron energy loss spectroscopy, low energy electron diffraction and high-resolution electron energy loss spectroscopy. The results show that the atomic ratio of oxygen to zinc in zinc oxide film is significantly dependent on sample annealing temperature and O₂ pressure. A stoichiometric zinc oxide film has been obtained under ∼10^− 4 Pa O₂ at about 400 K. A redshift of Fuchs-Kliewer phonon energy correlated with surface oxygen deficiency is observed.     

Non-Rigid Treatment of Interactions Between C60 Molecules

Abstract

Atom-atom van der Waals interaction energies are compared between bimolecular clusters of C₆₀ and circumcoronene, a model of graphite, with the aid of molecular mechanics. The minimum in the potential energy curve of the former is shallower and higher than the latter. Average equilibrium distance (3.08 Å) in the bimolecular cluster C₆₀–C₆₀ agrees well with the experimental value (2.96 Å). Equilibrium configurations of the C₆₀–C₆₀ cluster contain quite a few inter-cage atom-pairs in the repulsive region. Analysis of molecular as well as electronic structure in the closest possible approach under stringent conditions indicate that C₆₀ molecule is highly resilient ball.     

Normal-incidence reflectance of crystalline K(6)C(60), Rb(6)C(60), and Cs(6)C(60)

The structure factors and normal-incidence reflectances of the alkali-metal-doped fulleride crystals M(6)C(60) (where M = K, Rb, or Cs) were calculated, and the peak reflectances are in the 2-20% range for incident wavelengths of 9-17 ?, which indicates that C(60) may be a promising transmissive (spacer) material for normal-incidence mirrors that have relatively high normal-incidence reflectance in the x-ray region.     

C32C60C180、C60@C180富勒烯分子的压缩力学特性

采用Tersoff-Brenner势与L—J势的分子动力学方法，研究了双石墨层作用下C32、C60、C180以及C60@C180富勒烯分子的压缩力学特性。根据计算结果，讨论了几种富勒烯压缩过程中的变形、能量、压缩栽荷等的变化及其差异。研究表明，由于分子几何构形上的差异，压缩时，C180出现了明显的“塌陷”现象，“塌陷”过程中，能量及外载荷一度下降；几种富勒烯压缩时的能量吸收能力排序为：C32〉C60〉C60@C180〉C180，承载能力的排序为：C60@C180〉C180〉C60〉C32。     

Quantum Chemical Investigation of Two Fullerene C60 Molecules

The calculation data of four systems of two Cm molecules performed using a semiempirical CNDO/S - CI method obtained show three new, additional bands: 342.9 - 364.5, 427.3 - 437.1 and 481.6 - 495.9 nm not found in the calculations of single C₆₀ molecule and charge transfer band in the system of two C₆₀ molecules and two small charges.     

Nonvolatile Analog Memory Transistor Based on Carbon Nanotubes and C60 Molecules

A nonvolatile analog memory transistor is demonstrated by integrating C60 molecules as charge storage molecules in the transistor gate, and carbon nanotubes (CNTs) in the transistor channel. The currents through the CNT channel can be tuned quantitatively and reversibly to analog values by controlling the number of electrons trapped in the C60 molecules. After tuning, the electrons trapped in the C60 molecules in the gate, and the current through the CNT channel, can be preserved in a nonvolatile manner, indicating the characteristics of the nonvolatile analog memory.     

On the Effect of the Rotational State of C60 Molecules on Electronic Transport in the C60 Fullerite

Abstract

A phenomenological scenario is suggested in an attempt to explain controversies in the published data concerning the effect of orientational order on electronic transport in solid C₆₀. The main factor of crucial importance is the dependence of the charge hop probability on the mutual orientation of the molecules. Magnitude and the sign of the conductivity response to the changes in the rotational state of C₆₀ across the orientational phase transition are the results of the interplay between the changes in dynamic and static disorder that accompany the transition and may vary in the samples with different structure perfection.     

Coalesced C60 Molecules in Toluene Under Ultrahigh Pressure

Abstract

We present mass spectral evidence that coalesced C60 dimers and trimers were formed in toluene under 1.2-1.4 GPa at room temperature.     

Coalesced C60 Molecules in Toluene Under Ultrahigh Pressure

We present mass spectral evidence that coalesced C60 dimers and trimers were formed in toluene under 1.2-1.4 GPa at room temperature.     

Interaction of Molecular Oxygen with Solid C60

The interaction between oxygen and C₆₀ was studied in the regimes of combustion and reversible intercalation. The molecular nature of intercalated oxygen was shown by an isotope labelling experiment. Other gases such as nitrogen, argon, helium are intercalated with the same energetics as found for oxygen.     

硅、锗材料在Si(100)表面的生长研究

利用扫描隧道显微镜和超高真空实验装置系统进行了Si(10 0 )表面生长Si,Ge的实验研究。分析了所生成表面的形貌、结构等物理性质。研究表明 :Si在Si(10 0 )表面的同质生长可以形成纳米结构薄膜。Ge在Si(10 0 )表面生长形成规则的三维小岛。而在Si/Ge/Si(10 0 )多层膜上生长则形成大小二种三维岛。研究表明大岛具有Ge/Si/Ge的壳层结构     

Inelastic Neutron Scattering Study of Oxygen Intercalated C60

We have studied 0 ₂ intercalated C ₆₀ using both elastic and inelastic neutron scattering. The samples of stoichiometry (0 ₂ ) _x C ₆₀ with x 0.7 show a reduction in the order-disorder transition temperature T ₀ of 20 K with respect to pure C ₆₀ . The neutron diffraction pattern of the low temperature phase can be refined with the structural parameters of pure C ₆₀ whereby an expansion of the host lattice is registered. All 0 ₂ molecules are found on octahedral sites. The phonon spectrum of the host as well as the quasielastic response of the C ₆₀ cages above T ₀ are not visibly influenced by the guest molecules.