James Kay Graham Watson. 20 April 1936—18 December 2020

Abstract

J. K. G. (Jim) Watson was a world-leading authority on the basic theory of molecular rotation and vibration, especially renowned for his simplification of the rotational and rotation–vibration Hamiltonians (energy expressions). Other significant scientific achievements include the treatment of ‘forbidden’ rotational transitions in symmetric molecules and analysis of the spectrum of the H 3 + molecular ion, both of which have important astrophysical implications. Jim was a reticent individual who carried out much of his most important research solo, while at the same time he had a wide circle of collaborators who were often experimentalists seeking theoretical guidance. Although his most profound contributions were highly mathematical, he always endeavoured to present the ultimate results in a widely useful form.