Search for variation of fundamental constants: Strong enhancements in $X^2\Pi$ cations of dihalogens and hydrogen halides

TL;DR

This paper proposes using diatomic molecular ions with nearly degenerate energy levels to detect potential variations in fundamental constants, leveraging existing ion trapping techniques for promising candidate molecules.

Contribution

It introduces a novel method to search for variations in fundamental constants using specific diatomic molecular ions with enhanced transition effects.

Findings

Identification of promising molecular ions for variation studies

Proposal of a method based on nearly degenerate energy levels

Utilization of existing trapping techniques for experimental implementation

Abstract

We propose to use diatomic molecular ions to search for strongly enhanced effects of variation of fundamental constants. The relative enhancement occurs in transitions between nearly degenerate levels of different nature. Since the trapping techniques for molecular ions have already been developed, the molecules HBr$^+$, HI$^+$, Br$^+_2$, I$^+_2$, IBr$^+$, ICl$^+$, and IF$^+$ are very promising candidates for such future studies.