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

A detailed investigation is reported on polarization properties of laser in duced 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 4s sigmaE(2)Z(+) state and two- photon excitation for the 3p sigma, piD(2)Sigma (+), C-2 coproduct states. Degree of polarization was measured for the near-infrared ASE emitted from the single rovibronic levels. General expressions for degree of polarizatio n of fluorescence have been derived for double resonant excitation with par allel as well as perpendicular laser polarization. On the whole, ASE was fo und to be more strongly polarized than the calculation. Experimental values are compared with theoretical values in connection with the excitation-emi ssion rotational patterns. (C) 2001 Elsevier Science B.V. All rights reserv ed.