State-to-State Reaction Dynamics in Crossed Supersonic Jets: Threshold Evidence for Non-Adiabatic Channels in F + H2

Published

March 1, 1999

Author(s)

S A. Nizkorodov, W W. Harper, David Nesbitt

Abstract

The reaction of F + n-H6d2^ to form HF(υ,J) + H is studied in a crossed jet apparatus under single collision conditions, using high-resolution direct absorption spectroscopy to probe the nascent rotational HF distributions. The J-dependent reactive cross-sections into HF(Ņ=3,J) are investigated over a range of center-of-mass collision energies well below the 1.9 kcal mol^-1 barrier for adiabatic chemical reactions with ground state F(²P_3/2) atoms. The energy dependent reaction cross-sections decrease much more slowly with E_com then predicted by exact quantum calculations on the adiabatic F(²P_3/2) + H₂ surface (K. Stark and H. Werner. J. Chem. Phys., 1996, 104, 6515) In addition, product states in the HF(Ņ=3) manifold are observed that are energetically accessible only to the excited spin-orbit state F*(P1/2) + H₂(j=0,1) channel. These observations strongly sugget that non-adiabatic reactions with spin-orbit excited F*(P1/2) contribute significantly in the near threshold region, in good agreement with recent calculations by M. Alexander, H Werner and D Manolopoulos (J. Chem. Phys., 1998, 109, 5710) Finally, the feasibility of high-resolution IR laser Dopplerimetry on the nascent products is illustrated on collision free HF(Ņ,J) distributions formed from reactions of F + CH₄.

Citation

Faraday Discussions

Pub Type

Journals

Keywords

crossed molecular beam, potential energy surfaces, reactive scattering

Citation

Nizkorodov, S. , Harper, W. and Nesbitt, D. (1999), State-to-State Reaction Dynamics in Crossed Supersonic Jets: Threshold Evidence for Non-Adiabatic Channels in F + H₂, Faraday Discussions (Accessed December 9, 2024)