Knowledge Bank

Narrow level-crossing resonances have been observed by Stark tuning sublevels of the rotational line $J=1\to J=2$ of $CH3F$ at very low pressures. In our experiment, the level crossing width la about ten times smaller than the Doppler width of the absorption line. Saturation broadening of the level crossing dip has also been observed. Those level crossing signals have been obtained in zero Stark, field and also in a non-zero Stark field when an R.F, Stark field is superimposed. In the latter case, up to seven level crossing dips have been exhibited inside the Doppler width.