Collisional quenching andj-mixing rate constants for the3Dlevels ofCa+

Collisional relaxation and fine-structure mixing rate constants have been measured for the metastable $D$ doublet ${(3D}_{3/2},$ ${3D}_{5/2})$ of ${\mathrm{Ca}}^{+}$ ions in the presence of different neutral gases completing a previous work. Experimental results are given for He, Ne, Ar, ${\mathrm{H}}_2,$ ${\mathrm{N}}_2,$ and ${\mathrm{CH}}_4.$ These data have been obtained with a cloud of approximately ${10}^5$ ${\mathrm{Ca}}^{+}$ ions stored in a Paul trap at kinetic energies of around 1 eV. The investigated levels were populated by direct excitation of the corresponding $4S-3D$ transitions. The involved time constants were determined from the temporal evolution of the fluorescence of one of the resonance transitions, following the optical pumping of the $P$ level from the $D$ component. Comparison of our data with other similar experimental and theoretical work is finally presented.