Hyperfine Structures of Some Hg I Lines*

Measurements of the hyperfine structures of Hg lines λ5461, λ4358, and λ4047 have been made. These lines were obtained in absorption. Photographs of λ5461 were made with a 10-m double-passed grating spectrograph in the 11th order of 300 line per mm gratings, one 7.25 in. wide, and a second grating of 9.4-in. width. With the wider grating it was possible to resolve the central components of λ5461 and λ4358. Interferometric measurements of the structures of the three lines just mentioned were made using a modified DUDE procedure, particular attention being paid to determine accurately the over-all splittings of the 3S1 state for Hg199 and Hg201. In a similar fashion interferometric measurements of the hyperfine pattern of λ15 295 have been made.For λ5461 the interferometer had a resolving power of 2×106. A resolving power of 5×105 was used for λ15 295. For λ4358 the wider grating alone demonstrated a resolving power in excess of 106.The ratio μ201/μ199 as found from measurement of the over-all splitting of the 3S1 state was 1.1090±0.0007.