Surface Science: Foundations of Catalysis and Nanoscience

Chapter 8. Laser and Nonthermal Chemistry: Supplemental Material

The transformation of one kind of energy into another accompanies all processes in our world, and frequently also propels them. Many of these transformations - like the chemical reactions on catalysts or in sensors, or the mechanical friction or dispersion of charge carriers in microprocessors - take place at surfaces, or at the interfaces of solid materials.

SFB616 targets the clarification of these elementary procedures through the energy dissipation at surfaces. The program of the SFB616 is broadly designed and comprises the whole spectrum of stimulation and relaxation from the eV regime (particle interaction, laser stimulation, reactions and surfaces) through phonons and frictions losses in the meV regime to the meV area (electromigration)

Here is a short introduction to ultrafast surface photochemistry in the VUV.

The STM was invented by Gerd Binnig and Heinrich Rohrer who won the Physics Nobel Prize in 1986 for this achievement. You can learn more about Binning and Rohrer by visiting the Nobel Prize Archive

Lots of STM image galleries exist. For instance, here's one from the Technische Universität Wien.

Here's another from RHK Technologies.

And, of course, IBM since they invented it and also scientists at IBM (Manoharan, Lutz & Eigler) produced one of the images that is on the cover of the textbook.

Electrochemistry is also a part of this chapter. Much of electrochemistry occurs as the liquid/solid interface (Chapter 5) but in this chapter we focus on the charge transfer aspect of electrochemical reactions. Here's a basic refresher course in electrochemistry. For more on the nomenclature, definitions and standards of electrochemistry, visit this site. You can find application notes on electrochemical instrumentation and methods at this site maintained by Princeton Applied Research.

CCI Solar has an education page that provides links to lectures on electrochemistry, photoelectrochemistry and solar energy topics.

Find out more on hydrogen and fuel cells from the National Renewable Energy Laboratory (NREL). They also have a big program in solar energy.

This online tutorial on photovoltaics was developed by Stuart Bowden and Christiana Honsberg work at the Solar Power Labs at ASU.

Walther Nernst was not only the discoverer of the third law of thermodynamics and the Nernst equation of electrode potentials, but also he was the winner of the Nobel Prize in 1920 for his many discoveries in physical chemistry.

Questions and Exercises

  1. What are secondary electrons?
  2. What is the difference between a flux detector and a density detector?
  3. Does a substrate mediated process have to be a thermal process?
  4. What is a Feshbach resonance?
  5. How do electronic state lifetimes of chemisorbed and physisorbed species compare to the lifetimes of the same molecules in the gas phase?
  6. What properties of an excited state potential determine how much kinetic energy can be transferred to the excited molecule?
  7. When does DIMET become possible?
  8. What is the critical parameter that determines whether DIMET involves an excited electronic state or whether it occurs on the ground electronic state potential?
  9. (a) Show that the coverage decays exponentially for linear photodesorption with a constant cross section and absorbed fluence. (b) If the cross section decreases linearly with coverage, how does the coverage decay?
  10. What leads to deflections in off-normal ion desorption trajectories and recapture of slow moving ions or ions initially moving at large angles from the normal?
  11. Describe the difference in laser/plume interactions between ns irradiation and fs irradiation.
  12. Within the Marcus description, how does electron transfer between two solution phase species occur?
  13. Show that the vast majority of electron transfer between an aqueous ion and an electrode must occur with 0.3 nm of the ion's closest approach to the surface. Therefore electron transfer at a surface essentially only occurs when the ion or its solvation shell is in contact with the surface since 0.3 nm is roughly the size of the water molecule that could intervene between the molecule and the surface.
  14. Why does the current flow through a metal or semiconductor electrode depend on the bias voltage?
  15. Describe the temporal profile of a signal that is observed in a pump-probe experiment if the intermediate state lifetime is (i) infinitely short, (ii) much longer than the laser pulse widths, or (iii) comparable to the pulsewidth of the lasers used.

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