Rotational spectrum of molecular ion NH^+ as a probe for alpha- and m_e/m_p-variation
Abstract
We identify the molecular ion NH^+ as a potential candidate for probing variations in the fine structure constant alpha and electron-to-proton mass ratio mu. NH^+ has an anomalously low-lying excited Sigma state, being only a few hundred cm^-1 above the ground Pi state. Being a light molecule, this proximity is such that rotational levels of the respective states are highly intermixed for low angular momenta. We find that several low-frequency transitions within the collective rotational spectrum experience enhanced sensitivity to alpha- and mu-variation. This is attributable to the close proximity of the Pi and Sigma states, as well as the ensuing strong spin-orbit coupling between them. Suggestions that NH^+ may exist in interstellar space and recent predictions that trapped-ion precision spectroscopy will be adaptable to molecular ions make NH^+ a promising system for future astrophysical and laboratory studies of alpha- and mu-variation.
Keywords
Cite
@article{arxiv.1105.3530,
title = {Rotational spectrum of molecular ion NH^+ as a probe for alpha- and m_e/m_p-variation},
author = {K. Beloy and M. G. Kozlov and A. Borschevsky and A. W. Hauser and V. V. Flambaum and P. Schwerdtfeger},
journal= {arXiv preprint arXiv:1105.3530},
year = {2012}
}
Comments
8 pages, 1 figure