F. Muntean et Pb. Armentrout, Guided ion beam study of collision-induced dissociation dynamics: integraland differential cross sections, J CHEM PHYS, 115(3), 2001, pp. 1213-1228
The low energy collision-induced dissociation (CID) of Cr(CO)(6)(+) with Xe
is investigated using a recently modified guided ion beam tandem mass spec
trometer, in the energy range from 0 to 5 eV in the center-of-mass (CM) fra
me. The additions to the instrument, updated with a double octopole system,
and the new experimental methods available are described in detail. Integr
al cross sections for product formation are presented and analyzed using ou
r standard modeling procedure. A slightly revised value for the bond dissoc
iation energy of (CO)(5)Cr+-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 t
hreshold region for product formation. The resulting velocity scattering ma
ps are presented and discussed. Evidence of efficient energy transfer is ob
served from angular scattering of CID products. Experimental distributions
of residual kinetic energies are derived and extend to zero, the point of 1
00% energy deposition. This indicates that energy transfer is nonimpulsive
and probably associated with transient complex formation. For the first tim
e, the experimental residual kinetic energy distributions are compared with
the predictions of the empirical model used in integral cross section anal
yses. 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. (C) 2001 American
Institute of Physics.