MSS 2010 The Role of Vibrational Excitation on the Dynamics of the F( 2 P) + HCl FH + Cl( 2 P) Hydrogen-Transfer Reaction The Ohio State University Sara E. Ray, Gé W.M. Vissers, and Anne B. McCoy

van der Waals wells in reaction channels have been shown to have an effect on the reaction rates & dynamics in similar systems. * * D. Skouteris et al., Science 286, 1713 (1999) Motivation Possible to do full-dimensional ab initio calculations and full-dimensional dynamics.

Basis Sets Cl F F F Reactant Channel Product Channel

Advantages Possible to do full-dimensional ab initio calculations and full- dimensional dynamics. Challenges Open-shell systems often need multiple potential energy surfaces to accurately describe the reaction. Due to the large exothermicity (-33.1 kcal/mol) b, it is difficult to get the basis set large enough to fully describe the product channel. b. Deskevich et al. JCP 124(22), , (2006) Advantages and Challenges

Energies and Wave Functions F Cl l=1 λ=-1,0,+1 j HCl – monomer angular momentum j a – atomic angular momentum total angular momentum J=1/2 A – atomic spin orbit constant

Potential Energy Surfaces v=1 (2839 cm -1 ) Reaction FH+Cl Dissociation F+HCl Reactant Channel Product Channel v=2 (5629 cm -1 ) v=3 (8145 cm -1 )

Propagating the Wave Packet Reaction? Dissociation? Both?

Wave Packet Amplitudes v=1v=3v=2 Non-dissociated F-HCl  Dissociated  F + HCl Reacted  FH + Cl 35 % 62 % 30 % 67 %68 % 32 %

Electronic Distributions Product Channel Reactant Channel v=1 (2839 cm -1 ) Colinear Barrier Height: 1750 cm -1 Barrier Height – ZPE(420 cm -1 ): 1330 cm -1 ω

Electronic Distributions Product Channel Reactant Channel Colinear Barrier Height: 1750 cm -1 Barrier Height – ZPE(420 cm -1 ): 1330 cm -1 ω v=2 (5629 cm -1 ) Colinear Barrier Height: 8050 cm -1 Barrier Height – ZPE(420 cm -1 ): 7630 cm -1

Electronic Distributions Product Channel Reactant Channel ω Colinear Barrier Height: 8050 cm -1 Barrier Height – ZPE(420 cm -1 ): 7630 cm -1 Colinear Barrier Height: 8750 cm -1 Barrier Height – ZPE(420 cm -1 ): 8330 cm -1 v=3 (8145 cm -1 )

Electronic Distributions Product Channel Reactant Channel ω

Electronic Distributions – v=1 |j a,ω a > |3/2,3/2> |3/2,1/2> |1/2,1/2> Reactant Channel Product Channel

Electronic Distributions – v=2 |j a,ω a > |3/2,3/2> |3/2,1/2> |1/2,1/2> Reactant Channel Product Channel

Electronic Distributions – v=3 |j a,ω a > |3/2,3/2> |3/2,1/2> |1/2,1/2> Reactant Channel Product Channel

Rotational Distributions Black Bars – Reactant Channel Gray Bars – Product Channel v=1v=2v=3

Comparison to Cl + HCl The Cl + HCl studies showed that the amplitude of the wave packet that dissociated to the reactants was rotationally warmer than the amplitude that reacted. This is the opposite of what we found for F + HCl. v=2

Comparison to Cl + HCl  F + HCl is an exothermic reaction (-33.1 kcal/mol).  Cl + HCl is thermo-neutral.

Conclusions & Future Work  We can initiate the hydrogen-transfer reaction by vibrationally exciting the HCl stretch of the pre- reactive F-HCl complex with one, two, and three quanta of excitation.  The percent reaction increases with increasing vibrational excitation energy.  The electronic distributions are consistent with the amount of energy put into the system and the barrier heights of the three electronic surfaces.

Anne B. McCoy Gé W.M. Vissers Samantha Horvath Charlotte E. Hinkle Andrew S. Petit Annie L. Lesiak Bethany A. Wellen NSF for Funding Acknowledgements