PREDISSOCIATION OF AMMONIA A-STATE STUDIED BY MICROWAVE OPTICAL DOUBLE-RESONANCE SPECTROSCOPY

Homogeneous linewidths of the individual rotational transitions in the ÃX̃ system of ammonia were determined precisely by a microwave-optical double-resonance technique, where a single inversion transition in the ground state was selected by microwave radiation, and subsequent electronic transitions were observed by changes in the microwave absorption. The linewidths, which directly correspond to the à state predissociation rates, increase with J but are nearly independent of K. Small but distinct asymmetry in the line shape was observed for the first time. © 1990.