Frequency measurement of hyperfine transitions of the R(158)25-0 iodine line near the ¹S₀–³P₁ transition of ¹⁷⁴Yb

The a10 hyperfine transition of the R(158)25-0 line in molecular iodine serves as a viable optical frequency reference for laser cooling of 174 Yb via the 1 S 0 – 3 P 1 intercombination transition at 556 nm. This study reports a frequency measurement of the a 10 transition using an optical frequency comb, with an uncertainty of approximately 9 kHz. Additional hyperfine transitions of the R(158)25-0 line were also characterized, and a theoretical analysis of the hyperfine structure was conducted. These results facilitate laser-cooling experiments involving 174 Yb and contribute to the spectroscopic understanding of molecular iodine.