Line centers of a number of previously unresolved SF6transitions of the fundamental &ngr;3band have been observed and their frequencies have been determined relative to theP‐branch transitions of the CO210.6‐&mgr; laser. Measurements of dip widths at small saturation levels yielded a determination of the SF6&sngbnd;SF6cross section for phase interruption. Observation of a multiplicity of absorption line centers over the tuning range of theP(20) laser transition, several well within one SF6Doppler width of 29 MHz, verifies the complex nature of theP(20) line absorption found by other workers.