PHOTOFRAGMENT HELICITY CAUSED BY MATTER-WAVE INTERFERENCE FROM MULTIPLE DISSOCIATIVE STATES

Isolated diatomic molecules of iodine monochloride (ICL) were photodis sociated by a beam of Linearly polarized light, and the resulting grou nd-state CL atom photofragments were detected by a method that is sens itive to the handedness (helicity) of the electronic angular momentum. It was found that this helicity oscillates between ''topspin'' and '' backspin'' as a function of the wavelength of the dissociating light. The helicity originates solely from the (de Broglie) matter-wave inter ference of multiple dissociating pathways of the electronic excited st ates of ICI. These measurements can be related to the identity and to the detailed shapes of the dissociating pathways, thus demonstrating t hat it is possible to probe repulsive states by spectroscopic means.