Ion Dip Spectroscopy: A New Technique of Multiphoton Ionization Spectroscopy Applied toI2

Abstract
A new method of high-resolution multiphoton spectroscopy based on competition between ionization and stimulated-emission channels is described. It combines features of multiphoton photoionization with those of optical-optical double resonance. Results obtained for I2 demonstrate the method and identify intermediate states involved in multiphoton photoionization. The method offers the potential for extremely sensitive sub-Doppler spectroscopy of complex molecules.