Matrix Isolated Free Radicals: Chemistry and Physics Below 3 K
Wednesday, January 24, 2007
Chemistry and Physics Building, Planetarium
4:00 pm
Abstract
In this lecture, studies of atomic hydrogen, atomic deuterium and atomic nitrogen embedded in solid inert molecular matrices will be discussed. At first glance it would appear that chemical reactions would not occur in these systems. In fact, such reactions can and do proceed via quantum mechanical tunneling. For example, a deuterium atom can tunnel through an inert lattice. If it encounters a hydrogen molecule in the lattice, a free hydrogen atom is released and an HD molecule is formed. Such a reaction is called an exchange tunneling reaction. Hydrogen atoms can move through a molecular hydrogen lattice via a series of successive reactions. Recently we have observed some tantalizing evidence that Bose-Einstein condensation may be occurring in an ensemble of hydrogen atoms embedded in solid molecular hydrogen. Spin pair radicals have also been observed in samples of atomic nitrogen embedded in solid molecular nitrogen. A video tape will be shown of colorful explosive recombination events where nitrogen atoms recombine to form diatomic nitrogen molecules.
Biographical Data
David Lee was born (1931) and raised in Rye, N.Y., a small town on the coast of Long Island Sound. He attended Harvard University, graduating in January 1952. After two years of military service during the Korean War, he attended graduate school in Physics, attaining a Masters degree from the University of Connecticut (1955) and a Ph.D. from Yale University in 1959. In January 1959 he joined the Physics department of Cornell University as an instructor. Over the years, he worked his way up through the ranks at Cornell and is now the James Gilbert White Distinguished Professor of the Physical Sciences at Cornell. In 1972, along with his two Cornell colleagues (Robert C. Richardson and Douglas D. Osheroff), he participated in the discovery of Superfluid
3He. For this work, the group of three was awarded the 1996 Nobel Prize in Physics as well as the Buckley Prize of the American Physical Society and the Simon Prize of the British Institute of Physics. In addition to his work on Superfluid
3He, David has been active in research on superconductivity, spin polarized atomic hydrogen gas, solid helium, liquid
3He-4He mixtures and matrix isolated free radicals. He is a member of the National Academy of Sciences (USA), a foreign member of the Russian Academy of Sciences, and a fellow of the American Academy of Arts and Sciences, the American Association for the Advancement of Science, the American Physical Society, and the British Institute of Physics.
