Simplification of Rotational Spectra and Spectral Hole Burning by Selective Excitation Techniques in Microwave Fourier Transform Spectroscopy

Selective excitation techniques have been applied to pulsed microwave Fourier transform spectroscopy. The frequency selectivity in excitation has been reached either by a long, weak pulse, or by a DANTE multi-pulse sequence. The corresponding excitation spectra calculated from a density matrix theory are in good agreement with the experimental results. The selective excitation techniques have been combined with double resonance sequences in order to simplify the recorded one-or two-dimensional spectra. Furthermore, selective excitation techniques have been applied to burn ‘holes’ into rotational transition lines broadened by an inhomogeneous Stark field.