Structure in the Photoionization Continuum of SF6 below 630 Å

The absorption spectrum of neutral SF6 has been studied in the far-ultraviolet spectral region (100 to 630 Å) using the pure continuum radiated by the NBS 180-MeV electron synchrotron as a background source. A well-developed vibrational progression was observed in the 550–600-Å region. A Rydberg series of neutral SF6 was observed in the 450–500-Å region, converging to a limit at 26.83 (±0.04) eV. Additional absorption features were evident with peaks at 435 and 350 Å. Absolute absorption cross-section measurements were made at 539, 584, and 704 Å. The values obtained were 170, 70 and 100 Mb, respectively; the error in these measurements is thought to be no more than 25%.