TRANSIENT ABSORPTION, TRANSIENT EMISSION, AND FAST PASSAGE EXPERIMENTS IN MICROWAVE SPECTROSCOPY: THE MEASUREMENT OF $T_{1}$ AND $T_{2}$

Author Institution: Department of Chemistry, University of IllinoisStark switching microwave experiments on transient absorption and transient emission are described which allow the measurement of $T_{1}$ and $T_{2}$ in the J = 0 $\rightarrow$ 1 transition in OCS. We also demonstrate the effects of $\pi$/2 and $\pi$ pulses by using Stark switching, and we will discuss the measurements of $T_{1}$ and $T_{2}$. The theoretical and experimental analysis of fast passage phenomena in rotational spectroscopy is described in the pressure broadened limit. The phenomenon of Stark sweeping fast passage is carefully distinguished from the phenomena of transient absorption and transient emission which were treated earlier. We show that the observed response at the detector after Stark sweeping a molecular resonance through a fixed oscillator is a combination of off-resonance absorption and the beat between the fixed oscillator and the emission from the fast passage induced Polarization