Analytical study of level crossings in the Stark-Zeeman spectrum of ground state OH

TL;DR

This paper provides an analytical study of level crossings and avoided crossings in the Stark-Zeeman spectrum of ground state OH molecules, relevant for ultracold chemistry and quantum control, based on an exact solution of the Hamiltonian.

Contribution

It offers the first analytical analysis of spectral crossings in OH molecules using an exact Hamiltonian solution, improving understanding of non-adiabatic effects.

Findings

Exact solutions describe crossings and avoided crossings accurately.

Comparison with perturbation theory highlights differences in spectral features.

Insights into non-adiabatic transitions and Berry phases in molecular spectra.

Abstract

The ground electronic, vibrational and rotational state of the OH molecule is currently of interest as it can be manipulated by electric and magnetic fields for experimental studies in ultracold chemistry and quantum degeneracy. Based on our recent exact solution of the corresponding effective Stark-Zeeman Hamiltonian, we present an analytical study of the crossings and avoided crossings in the spectrum. These features are relevant to non-adiabatic transitions, conical intersections and Berry phases. Specifically, for an avoided crossing employed in the evaporative cooling of OH, we compare our exact results to those derived earlier from perturbation theory.