"Surface Processes and the Formation of Molecules in the ISM"
Wednesday, December 1, 2010- 4:00pm
John T. Yates, Jr.
Professor of Chemistry
University of Virginia, Charlottesville, VA 22904
Tel: (434) 924-7514; Fax: (434) 924-3710
It is now believed that molecule formation by surface chemistry occurs in adsorbed layers and in ice layers held on interstellar dust grains at temperatures in the range ~10 K to 100’s of K. Desorption of these molecules provides a major source for the complex gas phase species detected by radio astronomers. Much of this chemistry is initiated by photochemical processes induced by photons in the extreme ultraviolet. I will describe our infrared spectroscopic investigations of Lyman-α (10.2 eV) induced photochemistry of N2O molecules adsorbed on a high area SiO2; surface at 71 K, acting as a mimic of silicate dust grains in space. Evidence for the enhancement of combination reactions involving radical species on the surface is found, producing radical combination products such as NO2 and N2O4. An enhancement in the relative rate of formation of 5 and 20 is found for these two products, compared to the rate in the gas phase. In addition, I will describe our plans for the future, which include investigating the role of indirect photochemical excitation processes via photon excitation of the solid, a new photochemical route to be considered in astrochemistry. Such indirect photochemistry for both metallic and semiconductor surfaces is well documented in the last 40 years in the laboratory. Also, plans for the study of photochemical processes on C60 and graphene-like surfaces will be briefly discussed.
. M. Rajappan, C. Yuan and J.T. Yates, Jr., Journal of Chemical Physics, accepted.
John T. Yates, Jr. is a Professor of Chemistry and Shannon Research Fellow at the University of Virginia. He received his B.S. in Chemistry from Juniata College in 1956 and his Ph.D. in Physical Chemistry from M.I.T. in 1960. After three years as Assistant Professor at Antioch College, he moved to the National Bureau of Standards, where he was an NRC Postdoctoral Associate from 1963-1965 and continued as a Research Staff Member until 1981. From 1981-2006, he joined the University of Pittsburgh as the first R. K. Mellon Professor of Chemistry and Director of the Pittsburgh Surface Science Center. He joined the faculty at the University of Virginia in 2006 and established a new program in Surface Science. His specific research interests include surface chemistry and photochemistry, electronic excitation on surfaces, the dynamics of surface processes, adsorption, nanotubes, astrochemistry, and the discovery/development of new methods for surface chemistry research. He has published over 700 papers, co-authored or co-edited several books, holds patents for a variety of spectroscopy and surface techniques, serves on the editorial board of six different journals and two book series in surface science and catalysis, and remains active in undergraduate and graduate teaching. His professional honors and awards, though too many to list in full, include such distinguished achievements as the Department of Commerce Gold Medal in 1981, the Kendall Award of ACS in Colloid or Surface Chemistry in 1986, the First President's Distinguished Research Award at the University of Pittsburgh in 1989, the Alexander von Humboldt Research Award in 1994, election to the National Academy of Sciences in 1996, the Arthur W. Adamson Award for Distinguished Service in the Advancement of Surface Chemistry from the ACS in 1999, and the Peter Debye Award in Physical Chemistry from the ACS in 2007. According to the most recent Hirsch-index ranking of living chemists (Nov. 2010 Update), Yates is ranked 96th in the world for citations and associated research impact.