Metastable Dissociation of CH5 + Ions in the Methane Mass Spectrum

Abstract

Abstract The main dissociation channels of the CH5 + ion, i. e. have been investigated by a mass spectrometric method. The pressure dependences of the ratios I14,90/I17 and I13,26/I17, in the range from 4,4·10-4 to 1·10-4 Torr, were plotted. The two ratios depend linearly on the pressure in the mass spectrometer analyzer. Since the two straight lines do not pass through the origine the conclusion is drawn that, for both dissociation channels of the CH5 + ion, besides the collision-induced transitions, spontaneous transitions, i. e. pure metastable transitions, take place. The spontaneous dissociations constants (λ1 = 7,5·105 sec-1 , λ2 = 5,2·104 sec-1) and collision-induced dissociation cross-sections (σ1 = 5,25 · 10-16 cm2 , σ2 = 3,2·10-16 cm2) have been estimated. These results are discussed and compared with those reported by other authors.