OBSERVATION OF NA-2 RYDBERG STATES AND AUTOIONIZATION RESONANCES BY HIGH-RESOLUTION ALL-OPTICAL TRIPLE-RESONANCE SPECTROSCOPY

Na-2 Rydberg states have been observed for 10 less than or equal to n less than or equal to 119 and 0 less than or equal to J less than or equal to 9 using high resolution all-optical triple resonance spectroscopy and an ultrasensitive ionization detector. This represents the first example of high resolution triply resonant photoionization with cw lasers in any molecule. An improved ionization potential of Na-2 was estimated by extrapolation to be IP = 39478.75 +/- 0.04 cm(-1), corresponding to an improved molecular ion dissociation energy D-e = 7973.83 +/- 0.12 cm(-1). Four series, np (1) Sigma(u)(+), np (1) Pi(u), nf (1) Sigma(u)(+) and nf (1) Pi(u), were found and rovibrational interactions, l uncoupling, stroboscopic effects and Fano autoionization profiles were observed in the spectra.