CH Stretching Excitation in the Early Barrier F + CHD3 Reaction Inhibits CH Bond Cleavage
Weiqing Zhang,1,2
Hiroshi Kawamata,1
Kopin Liu1,*
Most studies of the impact of vibrational excitation on molecular
reactivity have focused on reactions with a late barrier (that
is, a transition state resembling the products). For an early
barrier reaction, conventional wisdom predicts that a reactant’s
vibration should not couple efficiently to the reaction coordinate
and thus should have little impact on the outcome. We report
here an in-depth experimental study of the reactivity effects
exerted by reactant C-H stretching excitation in a prototypical
early-barrier reaction, F + CHD
3. Rather counterintuitively,
we find that the vibration hinders the overall reaction rate,
inhibits scission of the excited bond itself (favoring the DF
+ CHD
2 product channel), and influences the coproduct vibrational
distribution despite being conserved in the CHD
2 product. The
results highlight substantial gaps in our predictive framework
for state-selective polyatomic reactivity.
2 State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Post Office Box 110 extension 11, Dalian 116023, People’s Republic of China.
* To whom correspondence should be addressed. E-mail: kliu{at}po.iams.sinica.edu.tw
