Donald Allan Ramsay CM. 11 July 1922 — 25 October 2007

Donald Allan Ramsay made significant contributions to the study of molecular spectra and molecular structure during a 60-year career at the Sussex Drive Laboratories of the National Research Council of Canada. He was an early pioneer in the technique of flash photolysis, or kinetic spectroscopy, opening new vistas in generating the spectra of unstable free radical molecules and probing their dynamics. His work on the amidogen radical, NH 2 , provided the first example of the Renner–Teller effect in molecular spectroscopy, resulting from interactions between electronic and vibration–rotational motions. He was one of the best-known figures in the field of molecular spectroscopy. Travelling widely, he had abundant and productive collaborations with scientists from all around the world. His seminal publications are a true indication of the energy, insight and originality that he applied to his scientific work.