In the beginning was H2+: Mass spectrometry and the molecular spectroscopy of gas-phase ions

Abstract The marrying of mass spectrometry with spectroscopic techniques for the study of mass selected ions corresponds closely to the half century, as the first mass-spectrometer based photodissociation spectrum experiment identified in this account was described in 1964. Starting from primitive beginnings, the field witnessed an explosion of techniques and interest in the 1970s and 80s, and has been further enriched in succeeding eras by the influx of new ion production approaches (like electrospray and MALDI), the development of new ion manipulation approaches such as supersonic beam expansion cooling and ion traps, and by the emergence of laser light sources in many varieties. A somewhat personal account of the evolution of this half century is given, with mention of many of the contributors.