Studies of Atomic Recombination of Nitrogen, Hydrogen, and Oxygen by Paramagnetic Resonance

The three-body volume recombination coefficient for neutral atoms A of nitrogen, oxygen, and hydrogen in their parent molecular gases M has been measured over a pressure range of one to ten millimeters at 300°K. The observations fit a reaction of the form A+A+[M]→ lim k1(A)A2*+[M],where k1(A), the rate constant, is found to be, respectively, k1(N) = 1.5 × 10−32 cm6/sec, k1(O) = 0.45 × 10−32 cm6/sec, and k1(H) = 6.5 × 10−32 cm6/sec. These determinations have an experimental fluctuation of ± 20%. Observations of the electron spin resonance (ESR) signal from the ground state of the atoms allowed direct determination of the atomic density. Measurements were made in a stream of flowing gas which carried the atoms through the ESR detection cavity. An atomic concentration of 1014 − 1016 cm−3 could be obtained in a CW electrodeless discharge. Surface recombination was inhibited by coating wall surfaces with a thin film of concentrated H2SO4. The work also includes some preliminary measurements of surface atomic recombination coefficients.