This paper reports the observation of the two-photon ionization of molecular cesium as a continuous function of laser wavelength in the 6200-6600-Å region with a tunable dye laser having a 0.18-${\mathrm{Cm}}^{-1\mathrm{}}$ linewidth. To the author's knowledge, it serves to illustrate the first extension to neutral molecular species of the important techniques of resonant multiphoton photodetachment spectroscopy. The resulting two-photon photoionization spectrum is intepreted in terms of the vibrational structure of the resonant intermediate molecular state.

• Received 23 March 1973

DOI:https://doi.org/10.1103/PhysRevA.8.2197