Isotope shifts and hyperfine structure of the Fe I 373.7 nm resonance line

TL;DR

This study measures isotope shifts and hyperfine structures of the Fe I 373.7 nm line across all stable isotopes, providing precise data on nuclear effects and magnetic interactions using high-resolution laser spectroscopy.

Contribution

It presents the first comprehensive measurement of isotope shifts and hyperfine structure for this Fe I transition, including the hyperfine constant for 57Fe.

Findings

Isotope shifts for all stable Fe isotopes are reported with high precision.

Hyperfine structure of 57Fe's excited state is characterized with a magnetic dipole constant.

Field and mass shift coefficients are derived from the measurements.

Abstract

We report measurements of the isotope shifts of the 3d6 4s2 a 5D3 - 3d6 4s4p z 5F4o FeI resonance line at 373.7 nm between all four stable isotopes 54Fe, 56Fe, 57Fe and 58Fe, as well as the complete hyperfine structure of that line for 57Fe, the only stable isotope having a non-zero nuclear spin. The field and specific mass shift coefficients of the transition have been derived from the data, as well as the experimental value for the hyperfine structure magnetic dipole coupling constant A of the excited state of the transition in 57Fe : A(3d6 4s4p z 5F4o) = 68.21(69) MHz. The measurements were carried out by means of high-resolution Doppler-free laser saturated absorption spectroscopy in a Fe-Ar hollow cathode discharge cell using both natural and enriched iron samples. The measured isotope shifts and hyperfine constants are reported with uncertainties at the percent level.