We have measured dissociative recombination of { HCl } ^ { + } with electrons using a merged beams configuration at the heavy-ion storage ring TSR located at the Max Planck Institute for Nuclear Physics in Heidelberg , Germany .
We present the measured absolute merged beams recombination rate coefficient for collision energies from 0 to 4.5 eV .
We have also developed a new method for deriving the cross section from the measurements .
Our approach does not suffer from approximations made by previously used methods .
The cross section was transformed to a plasma rate coefficient for the electron temperature range from T = 10 to 5000 K. We show that the previously used { HCl } ^ { + } DR data underestimate the plasma rate coefficient by a factor of 1.5 at T = 10 K and overestimate it by a factor of 3.0 at T = 300 K. We also find that the new data may partly explain existing discrepancies between observed abundances of chlorine-bearing molecules and their astrochemical models .