Spectroscopy: Single Molecule Spectroscopy

Textbooks in physics, chemistry, and biology abound in diagrams depicting single-particle, single-molecule or single-enzyme properties, reactions or interactions with their environment. Such pictures and the numbers associated with them, however, were, until recently, extrapolated from measurements performed on large ensembles of molecules, which only yield quantities averaged out over time, space, conformations and/or the local environment. Advances in detector sensitivity and improvements in instrument design do now provide scientists with tools to probe single molecules with light, and monitor their photophysical properties with exquisite sensitivity and time resolution. This spectroscopic information is used to explore the molecular structure, conformational dynamics, local environment, and intermolecular interactions. The collected data generate a wealth of new information on single-molecule physical chemistry or biomechanics, but also in polymer gel physics or glass dynamics and other domains of solid state physics.