Drift Tube Studies of Ion-Molecule Reactions at High and at Low Temperatures.

A temperature variable drift tube mass spectrometer apparatus has been used to determine the rate coefficients for the charge- and atom-transfer reactions O(+)N2 and O(+)+O2 (from 300K to 900K), He(+)+H2 and He+D2 (from 78 to 300K), as well as the association reactions R + 2R, where R is He, Ne or Ar (from 78K TO 300K). For the atom transfer reaction O(+)+N2, the rate coefficient decreases from (1.2 + or - 0.1) x 10 to the minus 12th power cu cm/sec to 0.5/10 to the minus 12th power cu cm/sec as the temperature is increased from 300K to 900K. For the charge transfer reaction O(+)+O2, the rate coefficient decreases from (2.1 + or - 0.2)x 10 to the minus 11th power cu cm/sec at 300K to half this value as the temperature is raised to 700K. These results are in good agreement with heated flowing afterglow results.