Studies of H+, H+2, and H+3 dissociative ionization fragments from methane, ethane, methanol, ethanol, and some deuterated methanols using electron-impact excitation and a time-of-flight method incorporating mass analysis

Kinetic energy distributions and relative intensities of energetic (≳1eV) H+,H+2, and H+3 dissociative–ionization fragments from methane, ethane, ethanol, and methanol have been measured using pulsed electron-impact excitation and a time-of-fight method incorporating a new mass analysis technique. The various deuterated analogs of H+, H+2, and H+3 fragments were also observed from CH3OD, CD3OH, and CD3OD. Results for these deuterated fragments show that energetic H+2 and H+3 fragments originate primarily from the −CH3 group, rather than from H atom extraction from both the−CH3 and −OH groups. Comparisons among the kinetic energy distributions of these light fragments from CH3OH, CD3OD, and CD3OH reveal no major isotope effects for fragment energies exceeding 2 eV.