Ion-molecule reactions at high temperature O{sub 2}{sup +} + CH{sub 4}

Studies of the reaction O{sub 2}{sup +} + CH{sub 4} have made it one of the best understood of all rearrangement interactions. The major product ion is CH{sub 2}OOH{sup +}. The reaction rate coefficient has been measured as a function of center-of-mass kinetic energy previously at temperatures from 93 to 545 K. We have used a flowing afterglow apparatus to study this reaction at higher temperatures. The reaction rate coefficient is 6 x 10{sup -12} cm{sup 3}/s at 300 K, and then increases dramatically - by a decade as the temperature climbs to 975 K. The apparatus is capable of reaching 1200 K, but above 1000 K the positive ion signal is presently dominated by K{sup +} ions due to thermionic emission from the stainless steel walls of the flow tube. This and other problems of high temperature operation will be discussed, and data on other reactions will be shown.