AUTOIONIZATION WIDTHS OF THE NO RYDBERG-VALENCE STATE COMPLEX IN THE 11-12 EV REGION

The photoion excitation spectra of (NO)-N-14 and (NO)-N-15 have been s tudied in the 105-112 Mn excitation region using high-order harmonic l aser spectroscopy. Utilizing the small bandwidth offered by this techn ique, the natural widths of prominent lines in this region have been m easured. These lines originate from interactions between high-lying Ry dberg levels converging to the NO+ electronic ground state and a 'new' NO valence state situated close to the latter state. The present meas urements show broad resonances corresponding to a decay time of 20-50 fs. This supports the interpretation that the decay takes place via ra pid electronic autoionization.