Sub-Doppler Optical Double-Resonance Spectroscopy And Rotational Analysis Of Na3

Based on rotationally resolved sub-Doppler spectroscopy and optical-optical double resonance (OODR) experiments on cold Na3 molecules in a collimated supersonic argon beam seeded with sodium, 51 rotational transitions selectively excited by OODR in the complex electronic A2A2 <-- XB-2(2) system of Na3 could be assigned unambigiously. Accurate values of the rotational constants and the molecular geometrical parameters have been derived from these measurements.