ELECTRONIC SPECTROSCOPY AND PREDISSOCIATION MECHANISM OF AR-NO IN THE3P RYDBERG STATES

Ar-NO in the (C) over tilde and (D) over tilde states, which are corre lated to two components of 3p Rydberg complex of NO, C(2)Pi and D(2)Si gma(+), were studied by using a mass-resolved (2 + 1) or (1 + 1') reso nance enhanced multiphoton ionization (REMPI) technique. The REMPI exc itation spectra were measured by monitoring parent Ar-NO+ or fragment NO+. The binding energies and the vibrational parameters are determine d for the Ar-NO (C) over tilde and (D) over tilde states. The (D) over tilde state was found to have surprisingly large D-0 values of 1044 c m(-1) for v(NO)' = 0 and 1004 cm(-1) for v(NO)' = 1, which are larger than 940 cm-l for Ar-NO+. From the analysis of these spectra, it was f ound that Ar-NO in the 3p Rydberg states predissociates into NO and Ar at different rates strongly depending on the Rydberg orbital characte r, the vibrational quantum number (v(NO)',) of NO moiety, and the inte rmolecular stretching quantum number (v(str)') of Ar-NO. Especially, t he interaction of the 3p Rydberg states with the nearest-neighboring ( B) over tilde state plays an important role in these v(NO)'- and v(NO) '-dependent predissociation of Ar-NO (C) over tilde(v(NO)' = 0, 1,2) a nd (D) over tilde(v(NO)' = 0.1). (C) 1998 Elsevier Science B.V. All ri ghts reserved.