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Theme 1 colloquium Structure and Dynamics of Molecules (Lecture)

Thursday 12 January 2017Add to my calendar
from 16:00
Prof. Rainer D. Beck (Ecole Polytechnique Fédérale de Lausanne (EPFL), Switzerland)

Rainer Beck EPFL jan17We present recent results from our laboratory on quantum state resolved reactivity and state-to-state scattering measurements for the dissociative chemisorption of methane on Ni and Pt surfaces1-8. Methane dissociation plays an important role in the steam reforming process used to convert methane and water into a mixture of hydrogen and carbon monoxide by heterogeneous catalysis. Using state-selective reactant preparation by rapid adiabatic passage in a molecular beam, we prepare the surface incident methane and water molecules in specific rovibrational quantum states and measure the state-resolved dissociation probability on a single crystal surface using surface analytical techniques such Auger electron spectroscopy, King & Wells beam reflectivity, and reflection absorption infrared spectroscopy (RAIRS). We also probe the quantum state distribution of the nonreactive scattered molecules by combining infrared laser tagging with bolometric detection. The results of our measurements provide evidence for mode- and bond-specificity as well as steric effects in chemisorption reactions and show that the dissociation of methane cannot be described by statistical rate theory but requires dynamical treatments including all internal vibrational and rotational degrees of freedom of the dissociating molecule. The detailed reactivity data obtained by our measurements serve as stringent tests for the development of a predictive understanding of these industrially important gas/surface using first principles theory.
[1] H.J. Chadwick and R.D. Beck, Chem. Soc. Rev. 45, p. 3576-94 (2016).
[2] L. Chen, H. Ueta and R.D. Beck, J. Phys. Chem. C, 119, 11199 (2015).
[3] P.M. Hundt, H. Ueta, M.E. Van Reijzen, H. Guo, R.D. Beck, Science, 344, 504 (2014).
[4] Hundt, Jiang, Van Reijzen, B. Jian, H. Guo, R.D. Beck, J. Phys. Chem. A, 119, 12442 (2015).
[5] P.M. Hundt, M.E. Van Reijzen, H. Ueta, and R.D. Beck, J. Phys. Chem. Lett., 5, 1963 (2014).
[6] H. J. Chadwick, P.M. Hundt, M.E. Van Reijzen, B. Yoder and R.D. Beck, J. Chem Phys, 140, 34321 (2014).
[7] F. Nattino et al, J. Phys. Chem. Lett., 5, 1294 (2014).
[8] H. Ueta, L. Chen, R.D. Beck, I. Colon-Diaz, and B. Jackson, Phys. Chem. Chem. Phys., 15, 20526 (2013).