Title: Controlling cold ion-molecule reactions in Coulomb crystals

Speaker: Brianna R. Heazlewood, Department of Chemistry, University of Oxford, UK

Abstract:

We can study reactive collisions between Coulomb-crystallised ions held within a linear Paul ion trap and cold neutral molecules.  The examination of such a proof-of-principle process, the charge exchange reaction between Xe⁺ and ammonia, is presented.  For quantitative analysis, a mass-sensitive detection method is adopted – with the ejection of all ions onto an external detector at a selected time.  This time-of-flight mass spectrometry (ToF-MS) approach removes ambiguity about the identities of dark ions: both the masses and relative numbers of all trapped species at the point of ejection can be ascertained directly from the ToF spectrum.  Combining ToF-MS detection capabilities with real-time imaging of the Coulomb crystal enables one to examine both the kinetics and the dynamics of ion-molecule reactions. In this way, accurate reaction rate constants and branching ratios can be calculated. The combination of a range of different cold molecular sources with linear Paul ion traps is discussed, along with the potential for controlling more than just the velocity of the neutral reactant species.

Coffee/tea and cake from 14:00

Email: brianna.heazlewood@chem.ox.ac.uk