Ion chemistry in octafluorocyclobutane, c-C4F8

Cross-sections for electron impact ionization of octafluorocyclobutane (c-C4F8) have been measured from 10 to 200 eV by Fourier transform mass spectrometry. No parent ion is observed and over half of the dissociative ionization yields C2F4+ and C3F5+. Eleven other fluorocarbon cations are produced with smaller cross-sections, giving a total ionization cross-section of (1.6 +/- 0.2) x 10(-15) cm(2) between 80 and 200 eV. Only CF,I and C2F(3)(+) react further with the parent molecule to yield C3F5+ as the primary product. No evidence of cationic polymerization was found. F- and C4F8- are formed by electron attachment at energies below 10 eV, but neither reacts further with c-C4F8. (C) 1998 Elsevier Science B.V. All rights reserved.