STM/STS observation of ferrocene derivative adduct to C60 on HOPG

The C₆₀ONCFn cycloadduct (Fn=ferrocene) was prepared in the reaction between C₆₀ and ferrocene oxime, the ferrocene derivative was bound to C₆₀ at the 6–6 bond by a heterocyclic oxygen–nitrogen–carbon ring; the compound was stable in air. The compound dissolved in dichloroethane was deposited on HOPG and observed by UHV STM/STS methods. The molecules of C₆₀ONCFn formed several-microns-long straight chains with clearly visible adducted groups pointing to one side of the chain. The STM/STS observations are discussed within the terms of semiempirical quantum chemical molecular modeling.     

Thermal properties of Fe-fullerene systems is reaction C60+Fe→Fe@C60 in solid fullerite possible?

Iron in the fullerite lattice binds fullerences in a sandwich type C₆₀FeC₆₀ complexes. At the concentration C₆₀Fe₂ it crystallizes in the monoclinic lattice. The structure is thermally unstable, with the energy release of 606 kJ·mol^?1 it returns to fee lattice. Two possible sites in the reconstructed fee lattice are discussed, Fe bond to C₆₀ and Fe inside the C₆₀ cage.     

Optically detected cyclotron resonance in a high mobility 2D electron gas

We study the properties of high mobility GaAs/GaAlAs quantum well structure by monitoring the microwave induced changes in the low-temperature photoluminescence of the 2DEG as a function of the external magnetic field. The most pronounced changes are observed at cyclotron resonance conditions, but weak features are also visible at cyclotron resonance replicas. Possible observation of microwave induced shift in the Landau-level structure of magneto-photoluminescence is reported in addition to the effects of carrier heating which are conventionally bracketed together with microwave irradiation.     

Carbon-iron arc plasma: Characterization and novel applications

The paper presents some novel applications of an arc plasma related to the synthesis of carbon nanostructures. The influence of iron on the final composition of solid products (e.g. fullerene content) is discussed. Pure and Fe-doped carbon plasmas were characterized by the optical emission spectroscopy. Dedicated to Prof. Jan Janča on the occasion of his 60th birthday. This work was supported by the funds of the State Committee for Scientific Research through the Department of Chemistry, Warsaw University within the project No. BW-1383/31/97 (to H.L.) and the grant No. 3 T09A 087 13 (to P.B.).     

Spectroscopic Study of C2 in Carbon Arc Discharge

The influence of self-absorption on intensity distribution in the rotational structure of the emission d ³II_gII → a ³II_u (0–0) band of C₂ radical was studied. The self-absorption effect was used for the determination of C₂ concentration in a DC carbon arc. The proposed method is general and may be used to other molecular bands of a similar rotational structure.     

Magnetic phase transitions induced by strong magnetic fields in Zn1-x Ga0.667x Cr2se4

Powders of the spinels Zn_1-x Ga_0.667x Cr₂Se₄ for x = 0.0, 0.1, 0.2, 0.3, 0.5 have been obtained. For these spinels magnetization measurements were carried out by induction in strong pulsed magnetic fields up to 20T, in the temperature range 2.9 K to 30 K.

For x = 0.0 (ZnCr₂Se₄) three phase transitions were observed, whilst for concentrations with x = 0.1, 0.2 and 0.3 there were only two and for x = 0.5 only one. A hypothesis on the magnetic structure of the various phases separated by these transition is put forward.     

Magnetic and structural investigations of GdMn2-GdNi2 intermetallic compounds

Magnetic and structural properties of the intermetallic system Gd(Mn_1-xNi_x)₂ were investigated. The 0?x?0.4 and 0.7<x?1 compounds are Laves phases of the MgCu₂ type. The remaining compounds 0.4?x?0.7. crystallize with the hexagonal structure. For single crystal GdMn_0.8Ni_1.2 the P6₃/mmc space group and the lattice parameters a=5.175 Å and c=16.731 Å are obtained. The magnetic properties of investigated series are investigated in stationary and in pulsed magnetic fields in the temperature range 2.6–700 K. For 0.4?x?0.8 two magnetic transitions are observed. In the paramagnetic range the χ^-1_M (T) is described by a Néel type variation and the molecular field coefficients N_{i j} are calculated. The localized character of the magnetic moment of Mn is observed.     

The microwave induced resistance response of a high mobility 2DEG from the quasi-classical limit to the quantum Hall regime

Microwave induced resistance oscillations (MIROs) were studied experimentally over a very wide range of frequencies ranging from 20 GHz up to 4 THz, and from the quasi-classical regime to the quantum Hall effect regime. At low frequencies regular MIROs were observed, with a periodicity determined by the ratio of the microwave to cyclotron frequencies. For frequencies below 150 GHz the magnetic field dependence of MIROs waveform is well described by a simplified version of an existing theoretical model, where the damping is controlled by the width of the Landau levels. In the THz frequency range MIROs vanish and only pronounced resistance changes are observed at the cyclotron resonance. The evolution of MIROs with frequency is presented and discussed.     

Thermal Stability of C60-Methylnaphthalenes Solvates

The crystalline solvates containing fullerenes and (di)methylnaphthalenes were investigated by thermal analyses and X-ray diffraction methods. It was found that C₆₀ with (di)methylnaphthalenes forms two types of stable solvates: either at the molar ratio 1:2 decomposing at temperatures close to 100°C or at 1:1 molar ratio decomposing in the temperature range 120–214°C. Crystalline lattice and thermal stability of the solvates depends on the structure of the solvent molecules. The strong solute-solvent interaction is also manifested by the modification of the C₆₀ absorption spectra in solution. The results are discussed using semiempirical quantum chemistry methods. This revised version was published online in August 2006 with corrections to the Cover Date.     

Theorem about existence and uniqueness of continuous solution of nonlocal problem for nonlinear hyperbolic equation

The aim of the paper is to give a theorem about the existence and uniqueness of the continuous solution of a non-linear differential hyperbolic problem with a nonlocal condition in a bounded domain. The Banach theorem about the fixed point is used to prove the existence and uniqueness of the problem considered. The results obtained in this paper can be applied in the theory of elasticity with better effect than the analogous known result with the classical initial condition.