Laser-induced amplified spontaneous emission from the 3d and nf Rydberg states of NO Original Research Article

Amplified spontaneous emission (ASE) from single rotational levels of 3dσ, πH 2Σ+, H′ 2Π and nf (n=4–6) Rydberg states of NO has been investigated through optical–optical double resonance excitation via the A 2Σ+ state. The H, H′→3pσ, πD 2Σ+, C 2Π (0,0) systems were rotationally resolved. The mixing of the C 2Π (v=0) state with the valence B 2Π (v=7) state explained the rotational pattern successfully. The degree of polarization of ASE for these transitions was measured and compared with the theoretical values of the corresponding resonant fluorescence. As the major ASE relaxation channels from the 4f and 5f (v=0) states, transitions down to the 3d and 4d (v=0) Rydberg series were identified, respectively. A new ASE relaxation pathway, 6f→5g, was found in addition to the 6f→5d band. The ASE from the 7f (v=1) state located above the ionization threshold was observed for the first time. The spectral profiles were discussed briefly in connection with the lifetimes of the upper levels.