Nascent rovibrational distributions of OH+ and OD+ in the A 3Πi state produced from the dissociative charge transfer reactions of He+ with H2O and D2O at thermal energy

The thermal-energy charge transfer reaction of He+ with H2O(D2O) has been investigated by observing the A 3Πi–X 3Σ− emission of OH+(OD+) at low pressures (<3 mTorr). The vibrational distributions in A 3Πi of OH+(OD+) are 0.66(0.55)v′=0, 0.20(0.26)v′=1, 0.10(0.13)v′=2, and 0.04(0.06)v′=3. The rotational distributions for v′=0–3 of OH+(OD+) are expressed by a single Boltzmann temperature of 1700±200 (1800±200) K. The fractions of the available energy deposited into rotation 〈 fr〉 and vibration 〈 fv〉 for OH+(OD+) are evaluated to be 4.9(5.5)% and 3.9(4.1)%, respectively, indicating that a large amount of the available energy is partitioned into the relative translational energy.