Absolute Cross Sections for Collision-Induced Dissociation Reactions of Highly Vibrationally Excited O2(+)X(sup 2) PI (sub 3/2,1/2g) and a(4) PI (sub 5/2,3/2,1/2,-1/2u) Ions.

摘要

During the past funding cycle, we have constructed and successfully integrated a state-of-the-art guided-ion beam mass spectrometer into the high-resolution photoion-photoelectron apparatus (Endstation 2) of the Chemical Dynamics Beamline at the Advanced Light Source (ALS) for the study of ion-molecule reaction dynamics. Preliminary tests on the performance of this guided- ion beam mass spectrometer have been made, indicating that the apparatus is performing well. Using this apparatus, we have measured the collision-induced dissociation (CID) and charge transfer (CT) cross sections for the collisions of O2+(v+=0-3) + Ar. Most importantly, by employing the differential pulse ion gate scheme along with the novel application of a wired ion gate to reject false coincidence ions, we have demonstrated for the first time a sensitive pulsed field ionization-photoelectron (PFI-PE)-secondary ion coincidence (PFI- PESICO) method for absolute cross section measurements of state-selected ion-molecule reactions. The high-resolution achieved by this PFI-PESICO method allows the unambiguous internal state selection of simple ions not only in specific vibronic levels, but also in given rotational states.