“…Moreover, the vibrational modes of BF 4 À and BF 3 located near 800 cm À1 [26] are not observed, either because of the high conductivity of the compounds or the low content of these residues. For T T above 400 8C, a strong band, for which the intensity increases with increasing treatment temperature, is observed at 1212 cm À1 and is ascribed to covalent C-F bond [12,27] in accordance with NMR data. 19 F NMR spectra at room temperature of CF x (300) and of CF x (300) outgassed at 150 8C, then exposed to air 2 h and 12 h. …”