Low-frequency electromagnetic radiation of hydrogen molecular gas: effect of the ortho-para conversion

Abstract

We calculate the rate of the spontaneous magnetic dipole radiation transitions from ortho-to para-states of the hydrogen molecule at room temperature with radiation wavelengths of about 0.01–0.1 cm. Exponentially small differences between the rotational energies and heat capacities of parahydrogen, orthohydrogen molecules and diatomic molecules consisting of different hydrogen atoms for high temperatures are derived.