surface physics

Prof. Roger G. Tobin

Research in surface physics at Tufts centers on understanding the interactions of atoms and molecules with metal surfaces. We employ a range of analytical techniques, including low-energy electron diffraction (LEED), Auger electron spectroscopy (AES), and temperature-programmed desorption (TPD), but our emphasis is on surface infrared spectroscopy and electrical resistance measurements.  Essentially all of our work is carried out under ultrahigh vacuum conditions.

One focus is on the effects of adsorption (the binding of atoms or molecules to the surface) on electronic conduction in metals. By localizing some electrons and providing scattering centers for others, adsorbed gases can have a significant effect on the electrical resistance and optical reflectance of thin metal films. These effects are relevant to gas sensing and may play an important role in the microscopic origins of friction. Our studies have shown that current models of these effects are inadequate, and may help to guide future theoretical development. Nevertheless surface resistivity has proved to be a useful tool for studying adsorption kinetics and interadsorbate interactions.  We are also exploring adsorption on ultrathin metal films, using the infrared vibrational spectrum of carbon monoxide as a probe of surface quality, and building towards an exploration of adsorption on metallic quantum wells.

For more information, please see our Surface Physics web site.

Selected Publications:

“The role of oxygen in hydrogen sensing by a platinum-gate silicon carbide gas sensor:  An ultrahigh vacuum study,” Yung Ho Kahng, Wei Lu, R.G. Tobin, R. Loloee and R.N. Ghosh , J. Appl. Phys. 105, 064511 (2009).

“Effects of interadsorbate interactions on surface resistivity:  Oxygen on sulfur-predosed Cu(100),” Chang Liu and R.G. Tobin, J. Chem. Phys. 128, 244702 (2008).

“On the potential of a chemical Bonds:  Possible effects of steroids on home run production in baseball,” R.G. Tobin, Am. J. Phys. 76, 15 (2008).