Rotationally state-selected ion-molecule reactions studied using pulsed-field ionization techniques

S. R. Mackenzie; Elizabeth J. Halse; F. Merkt; Timothy P. Softley

doi:10.1117/12.220857

18 September 1995 Rotationally state-selected ion-molecule reactions studied using pulsed-field ionization techniques

S. R. Mackenzie, Elizabeth J. Halse, F. Merkt, Timothy P. Softley

Proceedings Volume 2548, Laser Techniques for State-Selected and State-to-State Chemistry III; (1995) https://doi.org/10.1117/12.220857
Event: SPIE's 1995 International Symposium on Optical Science, Engineering, and Instrumentation, 1995, San Diego, CA, United States

Abstract

A new method for studying state-selected bimolecular ion-molecule reactions is presented here, based on the technique of zero-kinetic-energy (ZEKE) photoelectron spectroscopy. State selection of the molecular ions is achieved by two-color laser excitation to high Rydberg states, followed by pulsed-field ionization of the Rydberg molecules. The ions are produced in unique vibration-rotation levels with 100% discrimination against other ions present. They are formed in a supersonic beam and accelerated so as to react with other neutral molecules present in the beam, with controlled collision energy variable in the range 10 meV to 1 eV. The product ions are detected using a quadrupole mass-filter, and the reaction probability is determined as a function of collision energy and of reactant ion quantum state by measuring the product ion/parent ion ratio. State selection of N₂⁺, NO⁺, CO⁺ and H₂⁺ in a range of rotational levels has been achieved, all in the vibrational ground state, and preliminary measurements of the reaction H₂⁺ plus H₂ yields H₃⁺ plus H have been made. The study of other reactions is currently in progress. Some new observations have also been made in the same apparatus concerning the decay dynamics of high Rydberg states of N₂ which are of relevance to the state-selection process. The dynamics are followed as a function of principal quantum number and the effects of a weak electric field in promoting stabilization are observed.

Citation Download Citation

S. R. Mackenzie, Elizabeth J. Halse, F. Merkt, and Timothy P. Softley "Rotationally state-selected ion-molecule reactions studied using pulsed-field ionization techniques", Proc. SPIE 2548, Laser Techniques for State-Selected and State-to-State Chemistry III, (18 September 1995); https://doi.org/10.1117/12.220857

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