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Effects of Collision and Vibrational Energy on the Reaction of CH3CHO+() with C2D4 Ho-Tae Kim, Jianbo Liu, and Scott L. Anderson*
 

Summary: Effects of Collision and Vibrational Energy on the Reaction of CH3CHO+() with C2D4

Ho-Tae Kim, Jianbo Liu, and Scott L. Anderson*
Department of Chemistry, UniVersity of Utah, 315 S. 1400 E. RM Dock, Salt Lake City, Utah 84112-0850
ReceiVed: January 23, 2002; In Final Form: March 19, 2002
The reaction of acetaldehyde cations with ethene has been studied as a function of collision energy and
acetaldehyde vibrational state. REMPI through different vibrational levels of the B~ electronic state is used to
produce CH3CHO+ with controlled excitation in different vibrational modes. Reactions are studied in a guided
ion beam instrument, including measurements of product ion recoil velocity distributions. In addition, we
calculated the structures and energetics of 13 different complexes that potentially could serve as intermediates
to reaction. Three reactions are observed. Hydrogen atom transfer (HT) dominates at low collision energies
and is suppressed by collision energy and, to a lesser extent, vibration. The HT reaction is clearly direct at
high collision energies but appears to be mediated by a reactant-like precursor complex at low energies. The
most energetically favorable product channel corresponds to elimination of CH3 from an intermediate complex.
Nonetheless, this channel accounts for only 0.5% of the total product signal. The cross section for endoergic
charge transfer (CT) is strongly enhanced by collision energy in the threshold region. Over a wide range of
collision and vibrational energy, CH3CHO+
vibrational excitation enhances CT, but only 18% as much as for
the equivalent amount of collision energy. This effect is interpreted in terms of competition between the CT
and other product channels. The expected proton-transfer channel is not observed, an absence also attributed

  

Source: Anderson, Scott L. - Department of Chemistry, University of Utah

 

Collections: Energy Storage, Conversion and Utilization; Materials Science; Chemistry