Reactions of groundhyphen;state and metastable O2+ions with He, O2, N2, and CO2at thermal energies

摘要

Evidence is presented that some previous studies of reactions of O2+ions with various atoms and molecules referred to ion samples composed in part of ions in metastable (1Dand/or1S) states. This finding resolves the 3 orders of magnitude discrepancy between previous experimental and calculated rate coefficients for the O2+(3P)+He charge transfer process. Using a drift tube to distinguish, via arrival time differences, groundhyphen;state O2+(3P) and metastable ions, a rate coefficient of (3.5plusmn;1.5)times;10minus;11cm3/sec is obtained for the reaction, in good agreement with that obtained fromabinitiotheoretical calculations. Previous conclusions concerning reactions of O2+with O2and N2, however, remain valid since the difference in reactivity of groundhyphen;state and metastable O2+ions appears to be negligible in this case. The rate coefficient for the reaction O2++CO2has been determined to be (2plusmn;0.5)times;10minus;9cm3/sec for ions either in the groundhyphen;state or in metastable states.