Guided ion beam study of collision-induced dissociation dynamics: integral and differential cross sections

The low energy collision-induced dissociation (CID) of Cr(CO)6+ with Xe is investigated using a recently modified guided ion beam tandem mass spectrometer, in the energy range from 0 to 5 eV in the center-of-mass (CM) frame. The additions to the instrument, updated with a double octopole system, and the new experimental methods available are described in detail. Integral cross sections for product formation are presented and analyzed using our standard modeling procedure. A slightly revised value for the bond dissociation energy of (CO)5Cr+–CO of 1.43±0.09 eV is obtained, in very good agreement with literature values. Axial and radial velocity distributions for primary and product ions are measured at 1.3, 2.0, and 2.7 eV, in the threshold region for product formation. The resulting velocity scattering maps are presented and discussed. Evidence of efficient energy transfer is observed from angular scattering of CID products. Experimental distributions of residual kinetic energies are derived and extend to zero, the point of 100% energy deposition. This indicates that energy transfer is nonimpulsive and probably associated with transient complex formation. For the first time, the experimental residual kinetic energy distributions are compared with the predictions of the empirical model used in integral cross section analyses. Good agreement is observed within experimental uncertainties. A model for the distribution of deposited energy during collisional activation is derived on the basis of these experimental observations.