GUIDED ION-BEAM STUDIES OF THE GROUND-STATE O-2+(2-PI-G,V=0) REACTION WITH CH4 - EFFECT OF INTERNAL VERSUS TRANSLATIONAL ENERGY

Guided ion-beam mass spectrometry is used to study the reactions of methane with O2+ in its ground electronic and vibrational state. In addition to the three previously reported reaction products, CH2OOH+, CH3+, and CH4+, we also observe three other products, CH2O2+, H3O+, and CO2+. Reactions of excited O2+ ions are also examined and are shown to be more efficient than those for ground-state ions. The thermochemistry and potential-energy surfaces for this reaction are discussed as well as the effects of vibrational, electronic, and translational energy on the reaction system. A heat of formation for CH2O2+ of 201.5 +/- 1.6 kcal/mol is measured and tentatively assigned to the methyne hydroperoxy ion structure, HC-O-OH+.