Absolute frequency measurements and hyperfine structures of the molecular iodine transitions at 578 nm

TL;DR

This paper reports precise absolute frequency measurements of molecular iodine hyperfine components at 578 nm, providing valuable frequency references near ytterbium atomic clock transitions, using advanced laser and comb techniques.

Contribution

It introduces highly accurate hyperfine constants for iodine transitions at 578 nm, enhancing frequency reference standards for atomic physics research.

Findings

Measured 81 hyperfine components with 1.4×10^{-11} uncertainty

Derived hyperfine constants for four rovibrational transitions

Transitions are suitable as frequency references near ytterbium clock line

Abstract

We report absolute frequency measurements of 81 hyperfine components of the rovibrational transitions of molecular iodine at 578 nm using the second harmonic generation of an 1156-nm external-cavity diode laser and a fiber-based optical frequency comb. The relative uncertainties of the measured absolute frequencies are typically $1.4\times10^{-11}$. Accurate hyperfine constants of four rovibrational transitions are obtained by fitting the measured hyperfine splittings to a four-term effective Hamiltonian including the electric quadrupole, spin-rotation, tensor spin-spin, and scalar spin-spin interactions. The observed transitions can be good frequency references at 578 nm, and are especially useful for research using atomic ytterbium since the transitions are close to the $^{1}S_{0}-^{3}P_{0}$ clock transition of ytterbium.