Licentiate thesis: Internal energy effects in the Dissociative Recombination of small polyatomic molecular ions

by Mrs Iryna Kashperka (su.se molecular physics)

Monday 31 May 2010, 14:00 → 16:00 Europe/Stockholm

FA32

This licentiate thesis present experimental investigation on the heavy-ion storage ring CRYRING into the dissociative recombination of the following molecular ions with low energy electrons: CH3+, NO+H2O/NO+D2O and HCO+. As a result were calculated and investigated the cross section for vibrationally relaxed CH3+ molecular ions. It is of particular interest to measure the absolute rate of this reaction because this has never been measured before. The absolute rate is necessary to understand the CH3+ chemistry occurring in interstellar clouds, where an understanding of recent observations is being made extremely difficult by the lack of an accurate measurement of the absolute rate for the DR of vibrationally relaxed CH3+ ions. This is something that can easily be achieved in CRYRING via storage of the ions for a few seconds to allow the IR active modes to decay. Also the cross section and the first branching fraction were obtained for NO+H2O/NO+D2O ions, which help to understand the breaking bonds and formation preferable reaction pathways. By using the imaging technique was investigated how the available reaction energy is distributed among the products in the DR of HCO+. In particular the influence of rotational and vibrational population on the three electronic states of CO produced in the dominant product channel HCO++e→CO+H, and the calculation of the electronic branching fractions for this channel, was investigated. The main goal for such investigations is an understanding of one of the most dominating neutralisation chemical reactions which take place in the universe.