Excitation of the nitro group in nitromethane by electron transfer

Abstract

In this paper we report on complementary measurements on ion-pair formation in collisions between K atoms and CH 3 N0 2 molecules. The experiments were performed in a c.m. energy range from 20 up to 300 eV. Double differential cross sections were obtained by measuring the K + ion yield as a function of the scatter angle and as a function of the post-collision laboratory energy. On the other hand, relative total partial cross sections for the formation of CH 3 N0 2 -, N0 2 -, and 0 -were measured in the same energy range. The experimental results lead to the conclusion that in this energy range electron transfer takes place to three ionic states ofCH 3 NO; , a dominantly repulsive 2AI state and two 2EI states with relatively deep potential wells. 166 J. Chem. Phys. 95 (1).1

Negative ion formation in potassium–nitromethane collisions

“…12, we were able to detect nine new anions (Table 1), all peaks being observed with better resolution than before. 12 Electron transfer from potassium atoms to nitromethane molecules produces the parent ion CH 3 other minor intensity fragment ions. Fig.…”

“…The anionic states in nitromethane have been found by electron impact 3 to lie at 0.72, 2.4, 4.0, 5.6, 6.1 and 8.6 eV (Table 2), with the exception of the 2.4 eV state which has shown to be non-dissociative. In previous studies of ion-pair formation in collisions between K atoms and CH 3 NO 2 molecules, 12 both ionic and inelastic channels have been explored; three anionic states have been identified as intermediates for the final anion fragment production, especially a repulsive s* state of ( 2 A 1 ) symmetry and two bound states of 2 B 1 (p*) character. A vertical electron affinity of À2.16 AE 0.17 eV was obtained for the 2 A 1 (s*) and this anionic state decays by both autodetachment and dissociation into (CH 3 …”

“…Previous work on ion-pair formation in collisions of potassium atoms with nitromethane molecules have been reported including doubledifferential cross sections, obtained as a function of the scattered angle and the post-collision energy. 12 However, in this study only relative total partial cross section measurements were obtained and only three negative ions, O À , NO 2 À and CH 3 NO 2 À were detected. Steric asymmetry studies in electron transfer from potassium atoms to oriented nitromethane molecules have been performed by Brooks and co-workers, 13 showing no steric evidence for methyl-end attack favouring the participation of a dipole-bound state in the formation of CH 3 NO 2 À near the threshold.…”

Multiconfigurational second-order perturbation study of the decomposition of the radical anion of nitromethane

“…Indeed, the nitromethane radical anion (CH 3 NO 2 Ϫ ) can be formed from the neutral molecule (CH 3 NO 2 ) by different experimental methods: ͑i͒ electron impact, 6,7 ͑ii͒ collisions with atoms in highly excited Rydberg states, 1,2,6,8 or ͑iii͒ collisions with alkali atoms. 9 Gruzdkov and Gupta 10 have also proposed that CH 3 NO 2 Ϫ is an intermediate in the decomposition of amine-sensitized nitromethane shocked to 12-17 GPa peak pressures.…”

“…1 Later, Gutsev, Jena, and Bartlett 12 studied the valence-bound methylnitrite radical anion (CH 3 ONO Ϫ ) with similar methods. 9 or in electron impact experiments. 7 As it will be shown, no evidence of the existence of the isomerization channel toward CH 3 ONO Ϫ was obtained.…”