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The aim of this contribution is to study lanthanum containing fullerenes produced and treated under different conditions. The work was done using solid soot extract giving poorly resolved ESR spectra or separated lanthanofullerenes in solution showing well resolved ESR spectra. ESR experiments in connection with the mass spectrometry give information on the electronic states due to the electron transfer from the endohedral metal to the fullerene cage and the influence of oxygen on endohedral lanthanofullerene. The analysis of ESR spectra indicates the presence of up to nine octets of lanthanum containing fullerenes. These species have different stabilities. Furthermore, a very narrow single ESR line in the lanthanofullerene spectrum was detected having a linewidth ΔB=0.008 mT and ag-factor 2.0025. The electron transfer to the endohedral La@C82 molecule studied by voltammetry and electrochemicalin situ ESR experiments is described. The interaction of the lanthanofullerene with oxygen in solution is also studied. In different solvents the influence of oxygen on line broadening in the ESR spectra of La@C82 was observed. 相似文献
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T. Pichler M. Knupfer M.S. Golden T. Böske J. Fink U. Kirbach P. Kuran L. Dunsch C. Jung 《Applied Physics A: Materials Science & Processing》1998,66(3):281-285
82 using photoemission and electron energy-loss spectroscopy in transmission. In particular, the impact of the isomer symmetry
of the C82 cage (Cs or C3v) on the electronic structure and on the optical properties is analysed in detail. For both isomers, combined XPS and XAS
measurements of the Tm 4f and 4d states offer conclusive proof of a divalent encaged Tm ion. No significant change of the
valence of the rare earth ion upon changes in the cage symmetry is observed. From the C 1s excitation spectra we find a more
pronounced LUMO for the C3v(8) isomer, as is expected for the higher symmetry of the cage. Additional information about the optical properties was obtained
from the low-energy loss function. With use of a Kramers–Kronig analysis, the dielectric function, ε, and the optical conductivity,
σ, have been derived. ε(0) and the onset of the spectral weight are found to be 7.7 [12.8] and 0.6 eV [0.8 eV] for the Cs(6) {C3v(8)} isomer, respectively.
Received: 14 October 1997/Accepted: 28 October 1997 相似文献
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Wilk PA Gregorich KE Turler A Laue CA Eichler R Ninov V Adams JL Kirbach UW Lane MR Lee DM Patin JB Shaughnessy DA Strellis DA Nitsche H Hoffman DC 《Physical review letters》2000,85(13):2697-2700
New neutron rich isotopes 267107Bh and 266107Bh were produced in bombardments of a 249Bk target with 117-MeV and 123-MeV 22Ne ions at the Lawrence Berkeley National Laboratory 88-Inch Cyclotron. Identification was made by observation of correlated alpha-particle decays between the Bh isotopes and their Db and Lr daughters using a rotating wheel system. 267Bh was produced with a cross section of approximately 70 pb and decays with a 17(+14)(-6) s half life by emission of alpha particles with an average energy of 8.83+/-0.03 MeV. One atom of 266Bh was observed, decaying within 1 s by emission of a 9.29-MeV alpha particle. 相似文献
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S. Knorr A. Grupp M. Mehring U. Kirbach A. Bartl L. Dunsch 《Applied Physics A: Materials Science & Processing》1998,66(3):257-264
82 , Y@C82, and La@C82 in frozen solutions. We were able to determine the g tensors of these molecules by analysing magnetic field spectra at X-band
(9.5 GHz) and W-band (94 GHz) frequencies. Moreover, in Y@C82 we have investigated the hyperfine interaction of the 89Y nuclear spin (I=1/2) with the electron spin on the C82 cage. The principal values of the hyperfine tensor A and the relative orientation of g and A tensors were determined by applying
three- and four-pulse electron spin echo envelope modulation techniques (ESEEM).
Received: 3 September 1997/Accepted: 10 November 1997 相似文献
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[reaction: see text] We present an irreversible and efficient protease-based method for peptide synthesis which occurs independently of the primary specificity of proteases and also without proteolytic side reactions. The key feature of this approach is the combination of the substrate mimetics strategy with frozen state enzymology. Model reactions catalyzed by several proteases qualify this approach as a powerful concept in the direction of a more universal application of proteases as biocatalysts for peptide ligation. 相似文献
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