# Hyperfine-Resolved Spectroscopy of Dysprosium Monoxide (DyO)

## TL;DR

This paper studies the hyperfine structure of dysprosium monoxide to explore its potential for detecting new physics through nuclear Schiff moment measurements.

## Contribution

The study provides hyperfine parameters for DyO isotopologues, enabling optical cycling and precision measurements for symmetry-violating effects.

## Key findings

- Hyperfine parameters of DyO ground and excited states were measured for 161Dy and 163Dy.
- Results align well with relativistic quantum chemical calculations.
- DyO is shown to be a viable candidate for optical cycling and NSM searches.

## Abstract

We perform laser spectroscopy of dysprosium monoxide
(DyO) to determine
the hyperfine structure of the ground X8 and excited [17.1]­7 states
in the 161Dy and 163Dy isotopologues. These
dysprosium nuclei have nonzero nuclear spin and dynamical octupole
deformation, providing them high sensitivity to time-reversal-violating
new physics via the nuclear Schiff moment (NSM). The DyO molecule
was recently identified as being amenable to optical cyclingthe
basis for many laser cooling and quantum control techniqueswhich
makes it a practical candidate for NSM searches. The measurements
reported here are prerequisites to implementing optical cycling, designing
precision measurement protocols, and benchmarking calculations of
molecular sensitivity to symmetry-violating effects. The measured
hyperfine parameters are interpreted using simple molecular orbital
diagrams and show excellent agreement with relativistic quantum chemical
calculations.