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Vibrational mode-selected differential scattering of NH3 methanol ,,d1 , d3 , d4...: Control of product branching by hydrogen-bonded
 

Summary: Vibrational mode-selected differential scattering of NH3 methanol
,,d1 , d3 , d4...: Control of product branching by hydrogen-bonded
complex formation
Hungshin Fu, Jun Qian, Richard J. Green, and Scott L. Anderson
Chemistry Department, University of Utah, 315 South 1400 East RM Dock, Salt Lake City,
Utah 84112-0850
Received 19 September 1997; accepted 31 October 1997
We report a study of vibrational mode effects and differential scattering in reaction of NH3 with
CD3OD, CD3OH, and CH3OD over the collision energy range from 0.1 to 5 eV. At low collision
energies, abstraction of both methyl and hydroxyl D atoms is observed with roughly equal
probability, even though methyl D-abstraction should be favored on both energetic and statistical
grounds. Branching between the two abstraction reactions is controlled by two different
hydrogen-bonded complexes. Formation of these complexes is enhanced by NH3 umbrella bending,
unaffected by the NH3 symmetric stretch, and inhibited by collision energy. Endoergic proton
transfer is mediated at low energies by a third hydrogen-bonded complex, formation of which is
enhanced by both umbrella bending and the symmetric stretch. Charge transfer CT has a
significant cross section only when the NH3 umbrella bend excitation exceeds the endoergicity.
Collision energy and symmetric stretching appear to have no effect on CT. At high collision
energies all reactions become direct, with near spectator stripping dynamics. In this energy range
product branching appears to be controlled by collision geometry and there are no significant

  

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

 

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