Technological Advances in Atomic and Molecular Physics: Studies of electron interactions with molecular radicals, colloquium May 6, 2011

Leigh Hargreaves, Cal State Fullerton

Fundamental interactions between electrons and atoms or molecules underpin our understanding of diverse fields, ranging from industry and research focused applications such as laser and discharge physics, through to medical techniques such as radiation cancer therapy. Experimental research on interactions between electrons and atoms or molecules accordingly dates back almost a century to the pioneering Franck-Hertz experiment in 1914, which provided support of the Bohr model of the atom and was a precursor to modern Quantum Physics. Since that time, experimental atomic and molecular physics has become a mature field. The development of high resolution sources and detectors has enabled high precision studies into molecular electronic and vibrational spectroscopy and transition rates, magnetic bending of scattered particles allowed researchers to overcome the geometrical limits of their apparatus and coincidence methods allowed the very shape of an atom’s electron charge cloud to be mapped.

In this talk, I will review some of the commonly available techniques available to researchers today to study electron/molecule collisions. I will then discuss the development of a new type of experiment which enables electron collision studies with unstable molecules, particularly fluorocarbon radicals. Radicals are highly reactive atoms or molecules which exist for only very short times in any real system. However, in spite of their short lifetime, their high reactivity’s mean that radicals dominate the chemistry of any environment they find themselves in, one prominent example being the fluorocarbon plasmas used to dry etch computer chips. In spite of the importance of these species, laboratory studies on radicals are difficult using traditional methods, since one cannot easily prepare a study sample of such unstable species. The talk will focus on the techniques necessary to study these important targets, and the experimental challenges one faces to develop such an experiment.