New tools beget new science. One of the particular goals of our work has been the development of new laser-based spectroscopy methods, in the hopes that, over time, they will be taken up by others and become incorporated into the ‘toolset’ of the field. These contributions are best seen, not as completely new inventions, but as useful new twists on previous methods that add new capabilities to them. We have played a role in the development and promotion of resonant ion-dip infrared spectroscopy, a double resonance laser-based scheme that can be used to record the infrared spectra of individual conformational isomers and size-selected molecular clusters free from interference from other species present in the sample.

More recently, our group has developed a series of population transfer spectroscopy methods for studying conformational isomerization dynamics in flexible molecules. These methods combine conformation-selective excitation with conformation-specific detection, incorporating a collisional re-cooling step in between that enables the latter. Schemes which employ infrared, ultraviolet, and stimulated emission pumping (SEP) as laser excitation mechanisms have been developed and applied to a widening range of problems. A schematic diagram of the SEP hole-filling experiment is shown to the right. The methods make it possible to measure the product quantum yields as a function of conformation and vibrational level excited, and the energy barriers separating particular X→Y reactant-product pairs.