AVS 50th International Symposium
    Surface Science Monday Sessions
       Session SS1-MoM

Paper SS1-MoM7
Probing the Vibrational State-Resolved Gas-Surface Dynamics of Polyatomic Molecules Without the Laser

Monday, November 3, 2003, 10:20 am, Room 326

Session: Gas-Surface Dynamics
Presenter: A.L. Utz, Tufts University
Authors: D. Killelea, Tufts University
D. DelSesto, Tufts University
R. Smith, Tufts University
A.L. Utz, Tufts University
Correspondent: Click to Email
We describe an experimental approach that yields vibrational-state-resolved reaction probabilities for polyatomic molecules without the need for selective laser excitation of the target state. The method relies on a detailed knowledge of the vibrational structure of the molecule under study and its vibrational energy transfer dynamics in a supersonic expansion. In the case of methane, non-equilibrium cooling of vibrational states within polyads leads to the population of a single vibrationally excited state under easily obtained expansion conditions, even though several excited vibrational states would contain significant population under the nominal thermal conditions of the nozzle source. We apply this approach to extract state-resolved reaction probabilities for methane in its ground vibrational state (v=0) and @nu@@sub 4@ vibrational fundamental incident on clean, low-index nickel surfaces. State-resolved reaction probabilities obtained in this way are free from the vibrational-state averaging that clouds interpretation of beam-surface reactivity measurements and permit a more direct test of theoretical models of gas-surface reactivity.