Tim Sch&amul;fer1, Daniel P. Engelhart1, Fabian Gr&amul;tz1, Henrik Haak2, Daniel J. Auerbach3, Gerard Meijer2,4, Alec M. Wodtke1,3,5
1Institute for Physical Chemistry, Georg-August University of Göttingen, Tammannstr. 6
2 Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-14195 Berlin, Germany
3Department of Chemistry and Biochemistry, University of California Santa Barbara
4 Radboud University Nijmegen, 6525 AJ, Nijmegen, The Netherlands
5Department of Dynamics at Surfaces, Max Planck Institute for Biophysical Chemistry,
Am Fassberg 11, 37077 Göttingen, Germany
Having control over the reactant's degrees of freedom in chemical reactions provides a remarkable potential to deepen our knowledge of the dynamics on a molecular level. Especially, surface scattering experiments with molecular beams consisting out of quantum state selected molecules have had a tremendous impact on our understanding of the elementary steps in surface reactions.
Here, we present molecular beam deceleration methods to extend the molecular control onto the kinetic energy of the colliding molecules by reducing their translational velocity to almost standstill. This way, studies of the energy transfer between molecules and surfaces can be explored in much more detail compared to conventional molecular beam methods. I a first series of experiments we studied the absolute electron emission efficiency for metastable CO in the electronic a3? state on an Au(111) surface as function of temperature and velocity. While no velocity dependence could be observed we clearly see an enhanced emission efficiency at elevated temperatures.
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