PROJECTS

There are three major projects going on in the group at the present time.

Photochemical Production of Cyclic-N3

Cylic-N3 is a fascinating molecule for many reasons, not the least of which is that it is an excellent example of the geometric phase effect in molecules. The figure at the left shows the vibrational wave functions of cyclic N3 calculated with and without the GPE. One can easily see that not only are the energies of the states not correctly determined without including GPE, but the basic shapes of the vibrational wave functions are completely wrong unless the GPE is accounted for correctly.

 

Vibrational Promotion of Electron Emission

The experimental observation that vibrational energy of molecules that are undergoing bond breaking can exchange with electronic excitations of the metal represents a very interesting break down of the Born-Oppenheimer approximation. We are interested in trying to understand the basic chemical mechanism by which this takes place. We are also exploring new approaches to chemical sen

Science 290, 111-114 (2000)
 
sors based in this interesting physical chemistry.

Scattering of Laser-Prepared Molecules from Metal Surfaces

We have just finished the construction of a new advanced vacuum apparatus, designed to extend our capabilities to molecules that contain a Hydrogen atom. In this project we are using overtone pumping to excited molecules to high vibrational states investigating the way in which energy is exchanged in collisions with the surface. We will soon be installing an ion soft landing ion source to produce size selected nano-particles. In this way we will begin to understand how the electronic nature of the metal substrate may be used to tailor the chemical interactions at the interface.

 

 

In addition, there are a number of new and exciting interdisciplinary projects starting up through the Partnership for International Research and Education in Electron Chemistry and Catalysis at Interfaces.

 

Photochemical Production of Cyclic-N3 (power point presentation)

Additional Reading

  1. Photodissociation Dynamics of ClN3 at 203 nm: The NCl (a 1D / X 3S-) Product Branching Ratio, N. Hansen and A. M. Wodtke, A. V. Komissarov and M. C. Heaven, Chemical Physics Letters 368 568-573 (2003).
  2. Ion Dissociation Dynamics of the Chlorine Azide Cation (ClN3+) Investigated by Velocity Map Imaging, N. Hansen, A. V. Komissarov, K. Morokuma, M. C. Heaven and A. M. Wodtke, Journal of Chemical Physics 118 10485-10493 (2003)
  3. Velocity map ion imaging of ClN3 photolysis: Evidence of photolytic production of cyclic-N3. N. Hansen and A. M. Wodtke, Journal of Physical Chemistry (Charles Parmenter Festschrift) 107(49), 10608-10614 (2003).
  4. The Cl to NCl branching ratio in 248-nm photolysis of chlorine azide, Alec M. Wodtke, Nils Hansen, Niels Sveum, Jason Robinson, Scott Goncher and Daniel M. Neumark, Chem. Phys. Lett. 391 334-337 (2004).
  5. High Level ab initio studies of unimolecular dissociation of ground state N3 radical, Peng Zhang, Keiji Morokuma, Alec M. Wodtke, J. Chem. Phys. 122, 014106-1-11 (2005)

Accepted or In Press

  1. Photofragment Translational Spectroscopy of ClN3 at 248 nm: Determination of the Primary and Secondary Dissociation Pathways. N. Hansen, A.M. Wodtke, S. J. Goncher, J. Robinson, N. Sveum, D. M. Neumark, J. Chem. Phys., (in press)
  2. Two photoionization thresholds of N3 produced by ClN3 photodissociation at 248 nm: Further evidence for cyclic N3, Petros Samartzis, Jim Jr-Min Lee, Tao-Tsung Ching, Chanchal Chadhuri, Yuan T. Lee and Alec M. Wodtke (accepted to J. Chem. Phys.)

 

Vibrational Promotion of Electron Emission (power point presentation)

Additional Reading

  1. Direct multi-quantum relaxation of highly vibrationally excited NO in collisions with an O-covered Copper surface, H. Hou, Y. Huang, C.T. Rettner, S.J. Gulding, D.J. Auerbach, A.M. Wodtke, J. Chem. Phys. 110, 10660-10663 (1999).

 

  1. Enhanced Reactivity of Highly Vibrationally Excited Molecules on Metal Surfaces, H. Hou, Y. Huang, S.J. Gulding, C.T. Rettner, D.J. Auerbach A.M. Wodtke, Science 284, 1647-1650 (1999)

 

  1. Collisions and chemistry of super-excited molecules: experiments using the PUMP - DUMP - PROBE technique, Marcel Drabbels and Alec M. Wodtke, Feature Article for J. Phys. Chem. , 103 7142-7154 (1999)

 

  1. The Interaction of Highly Vibrationally Excited Molecules with Surfaces: Vibrational Relaxation and Reaction of NO(v) at Cu(111) and O/Cu(111), H. Hou, C. T. Rettner, D. J. Auerbach, Y. Huang, S.J. Gulding, A.M. Wodtke, Faraday Discuss. 113, 181-199 (1999)

 

  1. Fast multi-quantum vibrational relaxation of highly vibrationally excited O2, Rienk T. Jongma and Alec M. Wodtke, J. Chem. Phys., 111, 10957-10963 (1999)

 

  1. Observation of vibrational excitation and de-excitation for NO(v=2) scattering from Au(111): Evidence for electron-hole pair mediated energy transfer, Y. Huang, A.M. Wodtke C.T. Rettner, and D.J. Auerbach, Phys. Rev. Lett. 84 2985-8 (2000)

 

  1. Vibrational Promotion of electron transfer, Y. Huang, S.J. Gulding, C.T. Rettner, D.J. Auerbach A.M. Wodtke, Science 290, 111-114 (2000)

 

  1. The Dynamics of "Stretched Molecules": Experimental Studies of Highly Vibrationally Excited Molecules With Stimulated Emission Pumping, Michelle Silva, Rienk Jongma, Robert W. Field Alec M. Wodtke, Annual Reviews of Physical Chemistry 52, 811-852 (2001)

 

  1. Chemistry with stretched molecules, Alec Wodtke, Phys. Chem. Earth (C) 26(7), 467-471 (2001)

 

  1. Non-Arrhenius Surface Temperature Dependence in Vibrational Excitation of NO on Au(111): Evidence for the Importance of Surface Electronic States, Alec M. Wodtke, Huang Yuhui, Daniel J. Auerbach, Chemical Physics Letters 364(3-4) 231-236 (2002).

 

  1. Interaction of NO(v=12) with LiF(001): Anomalously large vibrational relaxation rates, Alec M. Wodtke and Yuhui Huang, Daniel J. Auerbach, Journal of Chemical Physics 118(17) 8033-41 (2003)

 

  1. Transport and focusing of highly vibrationally excited NO molecules, Daniel Matsiev, Jun Chen, M. Murphy, A.M. Wodtke Journal of Chemical Physics 118 9477-9480 (2003)

 

  1. Hexapole focusing of vibrationally excited molecules prepared by optical pumping, Jun Chen, Jason White, Daniel Matsiev, Michael Murphy, Alec M. Wodtke, Chem. Phys. 301(2-3) 161-172 (2004)

 

  1. Invited Chapter for Advanced Series in Physical Chemistry, World Scientific, Chuik Ng Series Editor, "Modern Trends in Chemical Reaction Dynamics Part II: Experiment and Theory". Ed.'s Xueming Yang and Kopin Liu, "Interactions of vibrationally excited molecules at surfaces: A probe for electronically non-adiabatic effects" Alec M. Wodtke, vol. 14, 383-408 (2005).

 

  1. Conversion of large amplitude vibration to electron excitation at a metal surface, J. White, J. Chen, D. Matsiev, D.J. Auerbach and A.M. Wodtke, Nature 433(7025),503-505, (2005).

 

  1. Invited Review in the International Reviews of Physical Chemistry. "Electronically non-adiabatic interactions of molecules at metal surfaces: Can we trust the Born-Oppenheimer approximation for surface chemistry?" Alec M. Wodtke, John C. Tully, Daniel J. Auerbach, International Reviews in Physical Chemistry, 23(4), 513-539 (2005).

 

  1. Vibrationally promoted emission of electrons from low work-function surfaces: Oxygen and Cs surface coverage dependence, J. White, J. Chen, D. Matsiev, D.J. Auerbach and A.M. Wodtke, Journal of Vacuum Science and Technology 23, 1085-1089 (2005)

 

Accepted or In Press

  1. Insensitivity of molecular trapping at surfaces to vibration. Alec M. Wodtke, Daniel J. Auerbach, Huang Yuhui, Chem. Phys. Lett. (in press)