Far-infrared amplified emission from the v = 1 autoionizing Rydberg states of NO

Far-infrared amplified emission from the v = 1 autoionizing levels of the ns (n = 9–14), np (n = 12–15) and nf (n = 8–14) Rydberg states of NO is reported in the gas phase. The dominant emission process for nf is assigned as the nf → (n − 1)g transition. Following the excitation of ns (n = 11–14), the emission from (n − 1)f energetically located above ns is detected. Following the excitation of np (n = 12 and 13), the emission from (n − 1)f is also detected. The absence of the emission from 11p leads to ∼3 ps as a threshold lifetime of the upper state needed for amplification.