ISSN:
0392-6737
Schlagwort(e):
Mössbauer spectra
;
Mössbauer effect
;
other γ-ray spectroscopy
;
Crystalline state (including molecular motions in solids)
;
Conference proceedings
Quelle:
Springer Online Journal Archives 1860-2000
Thema:
Physik
Notizen:
Summary C60 (Buckminsterfullerene) is isolated from organic solvents above 260 K as an f.c.c. solid with complete orientational disorder. The rotational dynamics are diffuse and isotropic, with a short (12 ps) correlation time at 300 K. Below 260 K, the solid forms in a simple cubic lattice withPa3 symmetry. The librational motion occurs by activated jumps with a correlation time of about 60 ns at 200 K. To gain further insight into the dynamics of C60, the compound C60Fe(CO)4 (I) (generously made available to us by A. Stephens and M. Green of Oxford University) has been studied by57Fe Mössbauer spectroscopy. As expected, the resonance at 90 K consists of a doublet with an isomer shift (relative to metallic iron) of 0.034(1) mm s−1 and a quadrupole splitting of 1.607(5) mm s−1. There is no significant temperature-dependent, intensity asymmetry of the doublet. The temperature dependence of the effect magnitude is well fit by a linear regression over the range 85〈T〈210 K. To elucidate the relationship of these results to the effect of the C60 moiety in I, further lattice dynamical Mössbauer studies have been carried out on (maleic anhydride) Fe(CO)4 (II), one of the few isolatable tetracarbonyl complexes of iron. For (II), the quadrupole splitting is 1.371(5) mm s−1 at 90 K, and the temperature, dependence of the isomer shift is smaller than it is for (I), while the temperature dependence of the recoil-free fraction is significantly larger in (I) than in (II).
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1007/BF02458895
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