Abstract
We present a study of H3 recombination performed at liquid nitrogen (LN2) temperatures on the two lowest rotational states of this ion, which belong to the two different nuclear spin states of the studied ion. A near infrared cavity ring-down spectrometer (~1381 nm) has been used to obtain the time evolution of concentration of both states during a pulsed microwave discharge. The discharge was ignited in a flowing gas mixture of He, H2 and Ar.
Concentrations of H2 around 2 x 1014 cm-3 assured that the ortho-H3 /para-H3 ratio was constant and equal to 1 during the whole discharge cycle. Both the binary and ternary He assisted recombination coefficient have been obtained aplhabin = 1.15 x 10-7 cm3 s-1 KHe = 0.67 x 10-25 cm6 s-1, respectively.