AVS 49th International Symposium
    Surface Science Wednesday Sessions
       Session SS1-WeA

Paper SS1-WeA2
Anomalous Reactive Scattering: Hyperthermal Energy Collisions of State-selected Bromine Ions on Pt(111)

Wednesday, November 6, 2002, 2:20 pm, Room C-108

Session: Gas-Surface Dynamics
Presenter: M. Maazouz, University of Notre Dame
Authors: P.L. Maazouz, University of Notre Dame
M. Maazouz, University of Notre Dame
D.C. Jacobs, University of Notre Dame
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The dynamics of scattering state-selected atomic and molecular bromine ions on Pt(111) are investigated across the hyperthermal energy regime (5 -100 eV). Scattered ionic products are measured with mass-, angular-, and velocity-resolution. Scattered Br@sub 2@@super -@/Br@super -@ product distributions are measured as a function of the incident Br@sub 2@@super +@/Br@super +@ collision energy, vibrational energy, and surface temperature. The yield for both atomic and molecular projectiles reveals an unusual behavior where negative ion conversion is most efficient for incident velocities near 7.6 km/sec. This sharp peak in the yield shifts to lower velocities with increasing surface temperature. A detailed analysis of the products' velocity distributions suggests an important interplay between charge transfer and energy transfer in this system.