Abstract

For methyl halides two states of molecular symmetry, + and −, exist that correspond to the two configurations of the molecule with respect to the symmetry plane determined by the three H-atoms, The molecule can switch to the inverse configuration by tunneling of the carbon-halide group through the symmetry plane. The inversion corresponds to a transition between + ↔ — states of the rotational levels that are split into a close doublet. In methyl halides the tunneling potential is very high and therefore the inversion frequency extremely low. Even at moderate pressures the linewidth resulting from pressure broadening of such inversion lines is large compared with the center frequency, which can be assumed to be zero.

© 1997 Optical Society of America