Transient effects in time-resolved infrared-microwave double resonance of ammonia

Abstract

A number of time-dependent absorption phenomena in laser-pumped infrared-microwave double resonance in ammonia have been studied in detail. A Stark-modulated, infrared-laser enhanced transient nutation experiment permits simultaneous measurement of both T1 and T2 for the (8,7) microwave inversion doublet. The result is 1/2πT1 = [(25.4±2.0) p+0.028] MHz and 1/2πT2=[(24.5±2.0) p + 0.087] MHz, where p (NH3) is in torr. Four-level double-resonance experiments allow a separate measurement of the inversion relaxation rate in the (9,7) absorption doublet, which is kβ= (12±3) ×106 sec−1⋅torr−1. The effect of partial saturation within the infrared Doppler velocity profile has also been investigated.