Results of an experimental study of binary recombination of para- and ortho-H-3(+) ions with electrons are presented. Near-infrared cavity-ring-down absorption spectroscopy was used to probe the lowest rotational states of H-3(+) ions in the temperature range of 77-200K in an H-3(+)-dominated afterglow plasma.
By changing the para/ortho abundance ratio, we were able to obtain the binary recombination rate coefficients for pure para-H-3(+) and ortho-H-3(+). The results are in good agreement with previous theoretical predictions.