BOUND-BOUND A 2-SIGMA+-X 2-PI TRANSITION OF NO-AR VAN-DER-WAALS COMPLEXES

The bound-bound excitation spectrum of the NO-Ar van der Waals complex associated with the NO A 2SIGMA+ -X 2PI transition has been measured by the resonance enhanced two-photon ionization (RE2PI) method using a time-of-flight (TOF) mass spectrometer. The van der Waals bands characterized by red-shaded rotational contours present no regularity in the progression. The photodissociation action spectra obtained by probing the NO A 2SIGMA+(upsilon' = 0, N' = 1 - 8) products have also been measured, and the binding energies (D0) of the complex in the A 2SIGMA+ and X 2PI states are determined as 44 and 88 cm-1, respectively. The action spectrum corresponding to the NO A 2SIGMA+ (upsilon' = 0, N' = 1 and 2) product shows several shape resonance peaks, which implies that the intermolecular potential between NO A 2SIGMA+ and Ar has a potential barrier of about 24 cm-1.