Activation Energy for the Three-Body Reaction of Helium Triplet Atom with Normal Helium

Abstract
From experimental determinations of the rate constants for the reaction He(3S1)+2 HeHe2(3Σu)+He , an activation energy, Ea=0.067 eV, was calculated. At 77°K, no contribution from this reaction was found in the afterglow of a pulsed discharge in helium; rather at 77°K the decay was found to be second order with a reaction constant about 2×10−9 cm3 atom−1·sec−1.