On walking in the footprints of giants

This article tells of a lifelong fascination with light, a messenger bearing information from realms ranging from the galactic to the submicroscopic. Personal interactions have shaped and informed this life journey. Accounts of some of the most important of these are related. Infrared and electronic spectra have been obtained, often for the first time, for many small free radicals and molecular ions-short-lived reaction intermediates in most chemical processes. The infrared spectrum of a molecule tells how its atoms vibrate with respect to one another and is as characteristic of the molecule as a fingerprint is of a person. Analysis of this spectrum provides sometimes surprising information about the structure and chemical bonding of the molecule in its lowest-energy electronic state. The electronic spectrum provides information on the molecule in more highly excited electronic states, in which its structure or reaction pattern may change or it may decompose.