摘要:

Molecular nanostructures, including fullerenes and nanotubes, are unique nanomaterials with interesting properties that suit them to a range of applications. This paper provides a review of current research into fullerenes and carbon nanotubes, the state of the art in terms of their synthesis and purification as well as the techniques used to characterize their extraordinary electronic and mechanical properties. Examples of the use of such nanomaterials are previewed and form the basis of the papers presented at this conference (author names denoted in text), dedicated to molecular nanostructures. ©2001 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1426809

出版商:AIP    

年代:1901

数据来源: AIP

摘要:

Solid solutions ofC59Nazafullerene inC60with concentrations up to10−4were produced in an electric gas discharge tube and by a heat treatment of(C59N)2dissolved in pureC60.The results on materials produced by the two methods are identical.C59Nis a stable monomeric substituent molecule in crystallineC60and may be heated to temperatures as high as 1300 K. The concentration of ESR active neutralC59Nmolecules at ambient temperatures depends on temperature history. ©2001 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1426810

出版商:AIP    

年代:1901

数据来源: AIP

摘要:

The stability of the azafullerenes of the type(C59N)Xwas studied by using IR, mass spectroscopy, optical and Raman experiments. X represents either hydrogen or an other cage ofC59N.Experimental data indicate thermal stability of the solid phase of the dimer up to 600 K followed by very slow degradation extending beyond 700 K. This is compared to our latest results on the temperature stability ofC59HNwhich was found to be stable only up to 540 K. A sudden change in the spectra at this temperature gives evidence for a transition to a new air stable phase. Since the mass spectra show no loss of hydrogen the new phase is claimed to be polymerizedC59HN.When heated in vacuum to about 700 K this phase dimerizes into(C59N)2.©2001 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1426811

出版商:AIP    

年代:1901

数据来源: AIP

摘要:

We investigated(C59N)2multilayer films, intercalated with different amounts of potassium, by electron energy loss spectroscopy and by synchrotron radiation techniques. For low K exposures, valence band photoemission shows, apart from a rigid shift towards higher binding energies of the whole spectrum, two new LUMO-derived peaks, indicative of a mixture of phases. One of the doped phases still preserves the dimer structure. At K concentrations, the(C59N)2dimer breaks up, as seen by HREELS, but the dimer phase can be recovered by distillation. C1s and K2p photoemission spectra show two K sites up to aboutK3C59Nand one K site for higher K concentrations. ©2001 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1426812

出版商:AIP    

年代:1901

数据来源: AIP

摘要:

Optimized geometries, energetics and vibrational spectra ofC59N,C59HNand(C59N)2have been calculated on the density functional (DFT) level, using B3LYP functional. Several isoelectronic model molecules(12C5914C)−and(12C59H14C)−have also been considered, for comparison. ©2001 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1426813

出版商:AIP    

年代:1901

数据来源: AIP

摘要:

Following a modified experimental procedure to the azafullerenes family ofC69N,a third less abundant isomeric(C59N)2heterofullerene was synthesized and spectroscopically characterized. Also, a solid state reaction of [70] fullerene withK2CO3afforded a mixture of five different structural isomers of homodimers(C70)2.©2001 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1426814

出版商:AIP    

年代:1901

数据来源: AIP

摘要:

We report temperature-dependent photoelectron spectra for a monolayer ofC60adsorbed on HOPG, as well as C1sx-ray absorption. This extends a previous report which showed the close similarity between the spectrum of the HOMO for the two-dimensional overlayer and that ofC60in the gas phase. The present work shows that intermolecular and molecule-substrate vibrations contribute strongly to the spectral lineshape at room temperature. Thus, vibrational effects are shown to be crucial for the proper understanding of photoelectron spectra, and thus the charge transport properties, forC60in contact with graphite and graphite-like materials. ©2001 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1426815

出版商:AIP    

年代:1901

数据来源: AIP

摘要:

Photopolymerization ofC60was performed on a gram scale via a new monomer transport method. After subsequent extractions of the raw polymer in organic solvents, 100mg dimer and 10mg mixture of soluble oligomers were yielded. The structures of the soluble fractions and the insoluble polymer were studied by optical spectroscopy and x-ray diffraction methods. According to IR and UV-VIS spectroscopic data, the obtained photodimer is identical to the(2+2)cycloadductC120prepared previously. In contrast to previous crystallization studies, a fast precipitation of the dimer from toluene gives rise to the formation of a solvent-free microcrystalline solid. The crystal structure of the pure dimer is fcc(a=14.05 Å)consisting of closely packed balls with the cycloadduct bonds oriented randomly along the 12 nearest neighbor directions. A linear relationship is found to exist between the fcc lattice parameter (a) and the average number of bonded neighbors(nB)in various photopolymerized structures. For insoluble polymersnB≈2is estimated, supporting previous photopolymer models of small ring or branched clusters. ©2001 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1426816

出版商:AIP    

年代:1901

数据来源: AIP

摘要:

We show that the absolute frequency position of the000band inC60andC70in several different matrices/environments is altered by less than 125 cm−1. In contrast, the effect of different environmental conditions for a multi-derivatised(C70Ph10)fullerene is shown be very pronounced (c.a.2500cm−1) noting also that the presence of 10 phenyl addends greatly perturbs the fullerene cage also up toc.a.5000 cm−1relative toC70.The effect of different addends upon [70]fullerene has been studied using phenyl and fluorophenyl addends, monitored by laser-induced luminescence. Different spectral characteristics are observed, thereby demonstrating that the fullerene cage is sensitive to the type of addend present. ©2001 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1426817

出版商:AIP    

年代:1901

数据来源: AIP

摘要:

There are many models of fullerene formation. Almost all of them are founded on the statistical approach. In this work the mechanism of transferring of carbon-helium plasma into the condensed state of carbon is described. This conclusion is caused by the generalization of the experimental results of the fullerene synthesis and the thermodynamic estimations considering the cluster charge. ©2001 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1426818

出版商:AIP    

年代:1901

数据来源: AIP