Measurement of transition frequencies and hyperfine constants of molecular iodine at 520.2 nm

TL;DR

This study precisely measured the hyperfine transition frequencies of molecular iodine at 520.2 nm using advanced laser and frequency comb techniques, providing detailed hyperfine constants and their rotational dependence.

Contribution

It introduces a novel measurement approach combining wavelength conversion and frequency combs to determine hyperfine constants of molecular iodine at 520.2 nm.

Findings

Transition frequencies with 1×10⁻¹¹ uncertainty

Hyperfine constants and their rotational dependence determined

Method demonstrates high precision in molecular spectroscopy

Abstract

We measured the transition frequencies of the hyperfine components in the four lines (P(34) 39-0, R(36) 39-0, P(33) 39-0, and R(35) 39-0) of the B-X transitions of molecular iodine at 520.2 nm. The 520.2 nm laser was generated by wavelength-converting the output of a 1560.6 nm external-cavity diode laser using a dual-pitch periodically poled lithium niobate (PPLN) waveguide. The frequencies were measured by counting the heterodyne beats between the laser stabilized at the frequencies of the hyperfine components and a frequency comb synchronized with a hydrogen maser. We determined the transition frequencies of the a1 components with relative uncertainties of 1*10-11; the uncertainty was limited by the impurity of the molecular iodine in the cell. From the measured hyperfine splitting frequencies, we calculated the hyperfine constants of these four transitions to obtain the rotational dependence of the excited-state hyperfine constants.