High resolution spectroscopic study of the first overtone of the NH stretch and of the fundamentals of the CH stretches in pyrrole Original Research Article

We have examined the first overtone NH stretching region and the fundamental CH stretching region of gas phase pyrrole (C4H5N), using high resolution Fourier transform spectra. The first overtone NH stretch has been rotationally analysed using an asymmetric top model and was found to exhibit two separate perturbations. These perturbations produce line splittings and anomalous intensity patterns in the spectrum which are briefly discussed. Hot band transitions, one of them red-shifted and others likely to overlap the main cold transition are also discussed. Three bands observed around 3100 cm−1 were also rotationally analysed, using a symmetric top Hamiltonian, and assigbed to three of the four closely overlapping fundamentals of the CH stretch vibrations. Evidence was obtained for the fourth expected CH fundamental.