Reactive collisions with conformationally controlled molecules

A new method to study conformer-specific effects in gas-phase ion-molecule reactions was developed. The cis- and trans-conformers of 3-aminophenol were spatially separated in a molecular beam and reacted with a Coulomb crystal of laser cooled Ca+ ions. The reaction of the cis-conformer was found to be twice as fast as the reaction of the trans-conformer. The difference in the rates could be explained by differences in the long-range ion-dipole interaction potential and
the results of adiabatic-capture-theory calculations agreed well with the experiment. A new experimental apparatus dedicated to conformer-specific ion-molecule experiments was designed and characterised. The new apparatus incorporates a time-of-flight mass spectrometer coupled to a linear quadrupole ion trap. The new mass spectrometer performs well and enables high resolution mass spectra of the trapped ions. The molecular beam machine in the new apparatus was tested and characterised by measuring OCS deflection profiles. A theoretical feasibility study for rotationally quantum-state selected ion-molecule reactions was performed and a new experiment was suggested and simulated.