Laser Spectroscopy of the y$^7$P$_J^{\circ}$ states of Cr I

TL;DR

This paper presents precise measurements and calculations of decay rates and isotope shifts for specific states of chromium I, validating advanced theoretical methods and demonstrating a cryogenic buffer gas source for future molecular experiments.

Contribution

It provides the first high-precision experimental data for decay rates and isotope shifts of Cr I states, benchmarking the CI+all-order theoretical approach for complex atomic systems.

Findings

Measured decay rates with 1% uncertainty

Measured isotope shifts with 0.5% uncertainty

Validated the CI+all-order method for Cr I states

Abstract

Here we report measured and calculated values of decay rates of the 3d$^4$($^5$D)4s4p($^3$P$^{\rm{o}}$)\ y$^7$P$^{\rm{o}}_{2,3,4}$ states of Cr I. The decay rates are measured using time-correlated single photon counting with roughly 1% total uncertainty. In addition, the isotope shifts for these transitions are measured by laser induced fluorescence to roughly 0.5% uncertainty. The decay rate calculations are carried out by a hybrid approach that combines configuration interaction and the linearized coupled cluster method (CI+all-order method). The measurements provide a much needed precision benchmark for testing the accuracy of the CI+all-order approach for such complicated systems with six valence electrons, allowing to significantly expand its applicability. These measurements also demonstrate operation of a cryogenic buffer gas beam source for future experiments with MgF molecules toward quantum blackbody thermometry.