Spectroscopic and related techniques in surface science for unravelling heterogeneously catalyzed reaction mechanisms Ludo Juurlink, Ph.D. Leiden Institute of Chemistry Leiden University, Leiden, the Netherlands Office: Gorlaeus Laboratories DE0.01 Email: l.juurlink@chem.leidenuniv.nl phone +31 71 527 4221 Course objectives:  At the this short course students can explain how surface science attempts to understand heterogeneous catalysis can outline how common experimental (spectroscopic) techniques reveal information on surfaces, adsorbates, and chemical reactions Understand why and how (supersonic) molecular beams are useful herein are informed on some recent examples in the field of gas-surface dynamics

Surface Science and Gas-Surface Reaction Dynamics Schedule Date Time Topics 14-Dec-17 11:00 – 11:50 Introduction: Surface Science for Catalysis Surface Crystallography Low Energy Electron Diffraction Scanning Tunneling Microscopy 12:00 – 12:50 Introduction to spectroscopic techniques Auger Electron Spectroscopy X-ray photoelectron spectroscopy Reflection Absorption InfraRed Spectroscopy Temperature Programmed Desorption 15-Dec-17 Controlling molecular impact: supersonic molecular beams Examples of combined use of SMB and Surface Science Examples from the recent literature on CH4 State-selected dissociation Mode-selected dissociation Bond-selected dissociation Stereodynamical effects

Strongly activated dissociation of methane CH4/Ni(111) and Ni(100) Lee, Yang, and Ceyer, J. Chem. Phys. 87, 2724 (1987) Holmblad, Wambach, and Chorkendorff, J. Chem. Phys. 102, 8255 (1995)

Some recent state-selected studies for CH4

Obtaining state resolution for CH4 Catalytic Surface Science - JuurlinkMarch 20, 2012 March 20, 2012 Obtaining state resolution for CH4 12/2/2018 ~35 kJ/mol ~18kJ/mol ~36 kJ/mol ~16 kJ/mol Juurlink, Killelea and Utz, Surf. Sci. Rep. 84, 69 (2009)

Juurlink, Killelea and Utz, Surf. Sci. Rep. 84, 69 (2009) State selectivity CH4/Ni(100) and Ni(111) CH4 dissociation is greatly enhanced by excitation of a stretch vibration. A quantum of antisymmetric stretch enhances reactivity approx as much as the same amount of kinetic energy The second quantum of antisymmetric stretch vibration helps as much as the first. The symmetric stretch is much more efficient in progressing along the reaction path than the antisymmetric stretch. v = 2 (3) v = 1 (1) v = 1 (3) v = 0 Juurlink, Killelea and Utz, Surf. Sci. Rep. 84, 69 (2009)

State selectivity CH4/Ni(100) and Ni(111) Again, stretch vibrations help; here v=1 (3) is more effective than Ekin! The 2nd quantum of antisymmetric stretch vibration does not help as much as the first. The antisymmetric bending vibration helps considerably less than the antisymmetric stretch on a “per energy basis” in v=3. v = 2 (3) v = 1 (3) v = 3 (4) State selectivity It matters where you put the energy v = 0 Energy efficiency The more activated the system the more crucial how energy is supplied. Juurlink, Killelea and Utz, Surf. Sci. Rep. 84, 69 (2009)

Mode selectivity CD2H2/Pt(111) |20> |11> |00> 5879.8 cm-1 70.4 kJ/mol 6000.2 cm-1 71.8 kJ/mol Beck et al, Science 302, 98 (2003)

It matters where you put the energy! Bond selectivity CD3H/Ni(111) C-D cleavage C-H cleavage CD3 CD2H CD4 CD3H Bond-selectivity. It matters where you put the energy! Killelea, Campbell, Shuman, and Utz, Science 319, 790 (2008)

Stereodynamical effects CH4/Ni(100) The initial state (0) or (1) indicates quantum number N, which is body rotation of the molecule. For the initial state N=J. For the upper state N can not have changed. 2 v=1 1 P(1) R(0) 2 1 v=0 Yoder, Regis, and Beck, Science 329, 553 (2010)

Surface Science and Gas-Surface Reaction Dynamics Schedule Date Time Topics 14-Dec-17 11:00 – 11:50 Introduction: Surface Science for Catalysis Surface Crystallography Low Energy Electron Diffraction Scanning Tunneling Microscopy 12:00 – 12:50 Introduction to spectroscopic techniques Auger Electron Spectroscopy X-ray photoelectron spectroscopy Reflection Absorption InfraRed Spectroscopy Temperature Programmed Desorption 15-Dec-17 Controlling molecular impact: supersonic molecular beams Examples of combined use of SMB and Surface Science Examples from the recent literature on CH4 State-selected dissociation Mode-selected dissociation Bond-selected dissociation Stereodynamical effects