PARAMETRIC 4-WAVE-MIXING IN THE 3D AND 4D RYDBERG STATES OF NO

The parametric four-wave mixing (PFWM) processes via the 3d sigma, pi H(2)Sigma(+), H'(2)Pi(+/-)(nu' = 2), and 4d sigma, pi O-2 Sigma(+), O' (2)Pi(+/-) (nu' = 0) Rydberg states of NO molecules are described. The analyses of the two-photon excitation functions and infrared emission spectra revealed that only the (2)Pi-component was involved in PFWM, This is in good accordance with the absence of amplified spontaneous e mission (ASE) in the (2)Sigma(+) and (2)Pi(+) components due to their predissociative character. Results provide some support for the mechan ism that the generation of the vacuum ultraviolet radiation was brough t by PFWM in which ASE served as a third driving wave.