Thiel Research Group
STM: Al-Pd-Mn quasicrystal, 15x15 nm2
Root-mean-square roughness, W, as a function of annealing
temperature, for various surfaces based on STM images.
Note: Al-Pd-Zn and Al-Cu-Co are quasicrystals.
STM: Ag on top of Ag/Si(111) - (?3x?3)R30° at 250 K
STM: Au islands on NiAl(110) at 300 K, 150x150 nm2
STM: S reconstruction of Ag(100) after heating to 300 K, 100x100 nm2
LEED: clean NiAl(110)
165eV at 120 K
We try to understand real problems in corrosion, lubrication,
heterogeneous catalysis and microelectronics (thin films) by creating
simple model surfaces and studying their chemistry on an atomic scale.
We then extrapolate this information back to the real system, where
such knowledge is often unobtainable, either because of a lack of
adequate experimental techniques or because of misleading extraneous
factors. In order to create a simple model of a surface chemical
process, we use single crystal surfaces with known morphology.
Ultrahigh vacuum provides the well-controlled chemical environment
necessary to study a reactive surface over a period of several hours.
We can deliberately expose the sample to a chosen gas in order to
change its surface composition and then characterize it.
There are three major projects currently underway in my group. These projects have all been selected because of their importance to fundamental and applied surface chemistry, and also because they are relatively new and unexplored. These projects involve:
- Metal Nanostructures on Semiconductors and Insulators
- Surfaces of Complex Metallic Alloys
- Stability and Coarsening of Metal Nanostructures on Metal Surfaces
We primarily use scanning tunneling microscopy (STM) and low-energy electron diffraction (LEED) in our studies. Examples are shown to the left and on the linked pages.
- Congratulations to Emma Kwolek for winning a 2014 Teaching Excellence Award, and to Holly Walen for winning a Dr. Ching Ching Chiu Fellowship for Women Doctoral Chemistry Students! Both awards are from the Department of Chemistry at Iowa State.