Two-dimensional microwave Fourier transform spectroscopy

Abstract

New two-dimensional correlation techniques in the field of pulsed microwave Fourier transform spectroscopy are presented. Five different pulse sequences were used to demonstrate connections between rotational transitions with well separated or with closely spaced frequencies. The introduction of two- and four-step phase cycles to select the desired coherence transfer pathways simplified the two-dimensional spectra considerably. Experiments were performed on methyl formate, norbornadiene, 1-chloro-1-fluoroethene, and vinyl cyanide. A theoretical treatment is given in terms of the density matrix formalism. The relationship between our experiments and similar nuclear magnetic resonance (NMR) techniques is also discussed.