title: Solid-state NMR (19F and 13C) study of graphite monofluoride (CF)n: 19F spin-lattice magnetic relaxation and 19F/13C distance determination by Hartmann-Hahn cross polarization.
abstract: Graphite monofluoride (CF)(n) was studied by solid-state NMR. (19)F spin-lattice relaxation time T(1) and second moment measurements of the (19)F line are presented. A "chair" conformation structure is found to be compatible with the experimental data. Relaxation is shown to be mainly due to paramagnetic oxygen. The presence of a molecular motion with an activation energy of 1.685 kJ.mol(-1) (202.7 K) is also evidenced. (19)F magic angle spinning (MAS) NMR and (13)C MAS NMR with (19)F to (13)C cross-polarization allows the determination of CF and CF(2) groups. Reintroduction of dipolar coupling by cross-polarization is used for C-F bond length determination (0.138 +/- 0.001 nm).
authors.affiliation: Matière Condensée et Résonance Magnétique, Université Libre de Bruxelles, CP 232, Boulevard du Triomphe, B-1050 Bruxelles, Belgium.
authors.forename: Jérôme
authors.initials: J
authors.lastname: Giraudet
authors.forename: Marc
authors.initials: M
authors.lastname: Dubois
authors.forename: André
authors.initials: A
authors.lastname: Hamwi
authors.forename: William E E
authors.initials: WE
authors.lastname: Stone
authors.forename: Pascal
authors.initials: P
authors.lastname: Pirotte
authors.forename: Francis
authors.initials: F
authors.lastname: Masin