Interactions of Ions With Hydrogen Atoms

Abstract

This progress report presents recent advances in developing a versatile technique for investigation of collisions of ions with open shell neutral intermediates. Combination of a 22-pole ion trap with a beam of H atoms allows accurate determination of rate coefficients at temperatures between 10 K and 300 K. New experimental results on hydrogen abstraction in collisions of CH + , CH 4 + and CH 5 + ions with H atoms are reported at temperatures between 10 K and 100 K. In the case of CH + and CH 4 + , large rate coefficients of 1.3 × 10-9 cm 3 s-1 and 6.0 × 10-10 cm 3 s-1 have been obtained at 50 K. CH + reacts with D atoms with a total rate coefficient of 2.4 × 10-9 cm 3 s-1 the branching ratio being 50 % for hydrogen abstraction and 50 % for atom exchange. For collisions of CH 5 + with H atoms rate coefficients of 9 × 10-12 , 1.3 × 10-11 , and 2.3 × 10-11 cm 3 s-1 have been determined at trap and nozzle temperatures of 10, 50, and 100 K, respectively. This indicates that this reaction is almost thermoneutral in contrast to thermodynamical data reported in the literature.

Ab initio potential energy surface of CH+2 and reaction dynamics of H + CH+

“…This is in agreement with theoretical expectations and experimental results, e.g. from Luca et al 33 and Federer et al 34,35 . Our QCT and ABC results are generally lower than the results of Halvick et al .…”

The Study of Cold Collisions Using Ion Guides and Traps

“…A short description of this setup has been given recently. 24 A detailed documentation of this sophisticated instrument is in preparation. 30 developed for exposing cold trapped ions to a slow effusive beam of H atoms.…”

Accurate global potential energy surface for the ground state of CH2+ by extrapolation to the complete basis set limit

“…Warmbier and Schneider 9 and Halvick et al, 7 as well as experimental data from Luca et al 55 and Federer et al 56 are also included.…”