Microwave-microwave and infrared-microwave double resonance spectroscopy of ammonia, methanol and trifluoroiodomethane

Double resonance spectroscopy involves the simultaneous application of two radiations to a sample at frequencies that are resonant with transitions in the sample molecule. There are many different types of double resonance methods. Two distinct techniques, 3-level and 4-level double resonance, can be discussed. In either case the higher power radiation is termed the pumping source (pump) and the lower power radiation is termed the signal source (probe).; The 4-level double resonance technique was used to study energy transfer by collisions in rotational energy levels of NH{dollar}sb3{dollar} with He and H{dollar}sb2{dollar} as collision partners. The rotational transitions were monitored and pumped by microwave radiation. The experimental details and results of the microwave-microwave double resonance study is presented in the thesis.; The 3-level double resonance technique is used for simplification and assignment of spectra. An infrared-microwave double resonance experiment was developed using a Fourier transform infrared spectrometer. A discussion of the results from the double resonance experiment is given.; An infrared-microwave double resonance spectrometer has been developed in our laboratory which employs a powerful microwave source, a cylindrical cavity sample cell, and a tunable infrared microwave sideband laser. With this apparatus, a ground state microwave transition, whose assignment and frequency are normally known, can be selected for pumping and the infrared spectrometer can then be scanned to locate vibration-rotation transitions that are affected by the pumped microwave transition. The results of a study of CH{dollar}sb3{dollar}OH including a lineshape analysis are given along with results from experiments on CF{dollar}sb3{dollar}I.