Negative Fragment Ions from Resonance Capture Processes

Abstract

An examination of negative fragment ions formed by resonance capture processes has been made using a mass spectrometer. It has been found in some cases that the various fragments for a particular molecule arise at the same ionizing energy, possibly by competing decomposition paths from the same state of the n;gative molecular ion. Other cases where the fragments do not arise at exactly the same energy may be explamed by close upper energy states of the negative molecular ion.. In general the observed ionization energies are greater than those calculated from the energies of bo~ds broken and electron affinities. Kinetic energy measurements on some of the more abundant fragments, I.e., CI-(CC4, CHa• CH2CI· CO) , 0-(S02, CO2, N20, NO), show that this excess energy is not translational.

Dissociative Electron Attachment to CCl4, CHCl3, CH2Cl2 and CH3Cl

“…It may be due to multiple fragmentation. Dorman [15] and Tsuda et al [21] observed CI-in the energy range between 6 and 9eV in agreement with our observation. Presumably, the resonance in the CH,CI--cross section is due to the dissociative attachment process e-+ CH,CI + CH,CI-+ H .…”

Influence of oxygen and water vapor on removal of sulfur compounds by electron attachment

“…4 occurred in the higher electron energy range. In the presence of water vapor, H-, 0-, OHwould be produced from the dissociative electron attachment to H,O (Moruzzi and Phelps, 1966;Massey, 1976;Schulz, 1960;Compton and Christophorou, 1967;Dorman, 1966). Those reactions consume electrons and decrease the collisions of electrons to sulfur compound molecules.…”

Low-energy elastic electron scattering by acetaldehyde

“…Measured cross sections for vibrational excitation by electron impact have shown both the π * resonance [10,11], at about 1.2 eV, and a further broad peak at 6.8 eV, assigned to one or more σ * resonances [10]. Other measurements have determined thresholds and, in some cases, relative cross sections for electronic excitation [8,10,[12][13][14][15][16], while still others have examined dissociative electron attachment [10,[17][18][19] and electron-impact ionization [20][21][22]. Burean and Swiderek [23] have studied the chemistry induced in condensed acetaldehyde by low-energy electron impact.…”