13C solid-state MAS NMR studies of the low temperature phase transition in fullerene C60

Autor:	Heyong He, John Foulkes, Jacek Klinowski, José Teixeira Dias
Rok vydání:	2000
Předmět:	Diffraction Phase transition Fullerene Chemistry Nutation Isotropy Spin–lattice relaxation Analytical chemistry General Physics and Astronomy Physical and Theoretical Chemistry Carbon-13 NMR Anisotropy
Zdroj:	Physical Chemistry Chemical Physics. 2:2651-2654
ISSN:	1463-9084 1463-9076
DOI:	10.1039/a909442c
Popis:	At the phase transition near 262 K, the 13C NMR spin–lattice relaxation time, T1, in static samples of pure C60 decreases from 31 to 0.8 s as the temperature decreases by less than 8 K, while X-ray diffraction patterns change little. Under magic-angle spinning T1 decreases from 46 to 0.8 s over only 2 K, while the onset of the phase transition is lowered to 255 K. NMR lineshapes of static samples are unchanged in the 280–235 K range, but the isotropic 13C chemical shift changes linearly by 1.88×10−3 ppm K−1. Uniaxial cage motion cannot average the chemical shift anisotropy to the value observed in static samples, and nutation must be present. Our tentative explanation of the results is based on differences in the nature of C60 cage motions at different temperatures.
Databáze:	OpenAIRE
Externí odkaz:	https://explore.openaire.eu/search/publication?articleId=doi_________::6c33bdc0337bf6ce33df82b45b73132d https://doi.org/10.1039/a909442c Zobrazit plný text záznamu