Radiative decay processes in the 6s and 7s Rydberg states of NO studied by three-color laser-induced amplified spontaneous emission spectroscopy

Abstract

A novel spectroscopic technique involving amplified spontaneous emission (ASE) is presented to excite single rotational levels of the 6sσT 2Σ+ and 7sσZ 2Σ+ Rydberg states of the NO molecule. In this excitation regime, the 3pπD 2Σ+ state, which is populated by the ASE deexcitation process from the 4sσE 2Σ+ Rydberg state, serves as the intermediate state. As the initial radiative decay channels form the T 2Σ+ and Z 2Σ+ states, the dipole allowed ASE transitions down to the nearest Rydberg states, i.e., T 2Σ+→5pσR 2Σ+ and Z 2Σ+→6pσY 2Σ+, are identified. The anomalous intensity distributions both in the excitation and emission spectra are well explained by s–d mixing and l uncoupling in the upper Rydberg states.