This chapter describes my research career, spanning the period from 1955 to 2000. My initial PhD work at the University of Southampton was concerned with the electronic structure and spectra of transition metal complexes and included studies of the electronic spin resonance (ESR) spectra of magnetically dilute single crystals. After a year at the University of Minnesota, I went to Cambridge University and for the next six years studied the ESR spectra of liquid phase organic free radicals. I commenced work on the microwave magnetic resonance (MMR) spectra of gaseous free radicals in 1965, and this work continued until 1975. I moved from Cambridge to outhampton in 1967. In 1975 I turned to the study of gas phase molecular ions, using ion beam methods. In the earlier years of this period I concentrated on simple fundamental species like H2^+ , HD^+, and H3^+
. In the later years until my retirement in 1999, I concentrated on the observation and analysis of microwave spectra involving energy levels lying very close to a dissociation asymptote.
structure , ions , microwave , resonance