Cross-sections for electron impact ionization of octafluorocyclobutane
(c-C4F8) have been measured from 10 to 200 eV by Fourier transform ma
ss spectrometry. No parent ion is observed and over half of the dissoc
iative ionization yields C2F4+ and C3F5+. Eleven other fluorocarbon ca
tions are produced with smaller cross-sections, giving a total ionizat
ion 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 polymeriza
tion was found. F- and C4F8- are formed by electron attachment at ener
gies below 10 eV, but neither reacts further with c-C4F8. (C) 1998 Els
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