Photofragment spectroscopy looks at excited states

An elegant way to study dissociative molecular excited states has grown up during the past few years. At the “New Vistas for Chemical Physics” session at the New York American Physical Society Meeting, Kent R. Wilson of the University of California, La Jolla, described “photofragment spectroscopy,” which enables Wilson and his coworkers to study both the excited states of a molecule and the photodissociation fragments it produces, by measuring the mass, translational energy and angular distributions of the fragments. Detailed information on bound excited states has long been available from ultraviolet and visible spectroscopy, but such information for dissociative states has been rare, although the dissociative states are the more common. Because some of the molecules Wilson has studied are among the major photochemically active pollutants of the atmosphere, the results may be interesting to environmentalists as well as to chemical physicists.