Polarization properties of laser induced amplified spontaneous emission from NO Rydberg states Original Research Article

A detailed investigation is reported on polarization properties of laser induced amplified spontaneous emission (ASE) from low-lying Rydberg states of NO. Two methods have been employed for populating s and p Rydberg members, namely, double resonant excitation for the 4sσE2Σ+ state and two-photon excitation for the 3pσ, πD2Σ+, C2Π states. Degree of polarization was measured for the near-infrared ASE emitted from the single rovibronic levels. General expressions for degree of polarization of fluorescence have been derived for double resonant excitation with parallel as well as perpendicular laser polarization. On the whole, ASE was found to be more strongly polarized than the calculation. Experimental values are compared with theoretical values in connection with the excitation-emission rotational patterns.