Abstract
We present a study of spin-dependent recombination of H3+ ions with electrons at 77 K. A near infrared continuous wave cavity ring down spectrometer (cw-CRDS) was employed to obtain concentration evolutions of the two lowest rotational states of H3+, which have different nuclear spin (ortho and para).
From the measured decrease of para-H3+ and ortho-H3+ densities during the afterglow, the effective recombination rate coefficient of H3+ was determined. Using para enriched hydrogen gas changed the [para-H3+]:[ortho-H3+] ratio.
From effective recombination rate coefficients, obtained at different ortho/para ratios, the recombination rate coefficients for individual spin states were calculated. The obtained individual values of the binary recombination rate coefficients are $^p\alpha_{bin} = (1.75\pm0.4)\times10^{-7} cm^3s^{-1}$ and $^o\alpha_{bin} = (5\pm3)\times10^{-8} cm^3s{-1}$ for para-H3+ and ortho-H3+, respectively.
Both values are in agreement with theoretical predictions.