Far infrared stimulated emission from the 8s and 8f Rydberg states of NO

Directional light emission of NO in the far infrared region has been analyzed. Two main stimulated emission channels around 27 μm (≈11 THz) and 14 μm for the 8sσ2Σ+(v = 0) level have been identified as the 8sσ → 7pσ and 8sσ → 6f transitions, respectively. Two dominant band systems around 19 and 21 μm for the 8f(v = 0) complex have been assigned to the 8f → 7g and 8f → 7dσ transitions, respectively. The possibility of the black body induced transitions is briefly discussed.