Hot Water Molecules from Dissociative Recombination ofD3O+with Cold Electrons

Abstract

Individual product channels in the dissociative recombination of deuterated hydronium ions and cold electrons are studied in an ion storage ring by velocity imaging using spatial and mass-sensitive detection of the neutral reaction fragments. Initial and final molecular excitation are analyzed, finding the outgoing water molecules to carry internal excitation of more than 3 eV in 90% of the recombination events. Initial rotation is found to be substantial and in three-body breakup strongly asymmetric energy repartition among the deuterium products is enhanced for hot parent ions.

Dissociative Recombination Measurements of Chloronium Ions (D2Cl+) Using an Ion Storage Ring

“…This ∼3 eV corresponds well to the E 0 of the three-body channel, to within the energy resolution of our KER distribution analysis for the two-body channels. Similar KER distributions, extending from the two-body E 0 value and going down to the three-body fragmentation E 0 value, have been observed in DR of + H 3 , D 2 H + , D 3 O + , and DCND + (Strasser et al 2002;Buhr et al 2010aBuhr et al , 2010bMendes et al 2012). The maximum energy released here by either two-body DR channel at matched beams' velocities is 7.9 eV.…”

“…However, the pulse heights provide information on the fragment masses. The detector is described in detail elsewhere (Buhr et al 2010b) and has been used successfully for DR studies of D 3 O + , D 2 H + , DCND + , and NH + (Buhr et al 2010a(Buhr et al , 2010bMendes et al 2012;Yang et al 2014). Here we describe only those aspects of the detection method relevant for the present study.…”

REASSESSMENT OF THE DISSOCIATIVE RECOMBINATION OF N2H+AT CRYRING

“…Therefore, the discrepancy between the temperature dependencies cannot be assigned to different degrees of vibrational excitations in the ion populations. N 2 H + has a rather high dipole moment of ∼3.4 D (Havenith et al 1990) and we believe, therefore, that the storage time was sufficient to give the ion population a rotational temperature of about ∼300 K, though we cannot be absolutely certain about this temperature (e.g., Buhr et al 2010). Assuming that the rate coefficient for the DR of N 2 H + has power-law dependencies on both the electron temperature and the rotational temperature of the ions implies a rotational temperature dependence of approximately T 0.84 rot for T rot > 200 K in order to reach consistency between the present results and those reported by Poterya et al (2005) and Lawson et al (2011).…”

Interstellar Water Chemistry: From Laboratory to Observations

“…A number of experiments have been undertaken on this system 204,205,206,207 , and the cur- 175 for the reaction with H + 3 at room temperature, 300 K, is 5 × 10 −9 cm 3 s −1 , and the estimated value using the trajectory scaling model is also this value. At a temperature of 10 K, the predicted rate coefficient would be approximately a factor of 4.6 greater.…”