Thev3band of the molecular ion H3O+

Abstract
The perpendicular v 3 fundamental band of the H3O+-ion has been remeasured with a colour centre laser. Improved results have been achieved by combining our experimental data with the recently published line positions of Begemann et al. and Bunker et al. For the first time the l-type doubling constant for the a-species has been determined, together with an additional l-type resonance parameter which describes the splitting of the (Kl) = -2 level.