Ion–Molecule Reaction Studies from 300° to 600°K in a Temperature-Controlled Flowing Afterglow System

Abstract

The flowing afterglow technique for ion-neutral reaction rate constant studies has been modified to cover a range of gas temperature from 82° to 600°K. The experimental apparatus is described and rate constants for six reactions between 300° and 600°K are reported. The reaction of He+ with N2 is found to have a rate constant 1.2 × 10−9 cm/3sec, independent of temperature in this range. The reaction of O+ with CO2 has a rate constant 1.1 × 10−9 cm3/sec at 300°K, decreasing slightly to 8 × 10−10 cm3/sec at 600°K. The reaction of N+ with O2 appears to have a rate constant 6 × 10−10 cm3/sec throughout this temperature range. The rate constant for charge transfer of N2+ with O2 is measured to be 4.7 × 10−11 cm3/sec at 300°K, decreasing to about 2 × 10−11 cm3/sec at 500°K. The rate constant for the reaction of O+ with O2 decreases from 2 to 1.3 × 10−11 cm3/sec, and the rate constant for O+ + N2 decreases from 1.2 × 10−12 cm3/sec to about 6 × 10−13 cm3/sec between 300° and 600°K.