Paul R. Krehbiel received the B.S. and M.S. degrees in electrical engineering (with a physics option) from the Massachusetts Institute of Technology, Cambridge, MA, USA, in 1963 and 1966, respectively, and the Ph.D. degree in physics from the University of Manchester Institute of Science and Technology, Manchester, U.K., in 1982. He is currently a Professor of physics with the Physics Department and the Langmuir Laboratory for Atmospheric Research, New Mexico Institute of Mining and Technology, Socorro, NM, USA.