Ortho-para transition in molecular hydrogen

TL;DR

This paper calculates the radiative ortho-para transition rate in molecular hydrogen, revealing a lower value than previous estimates, highlighting the transition's sensitivity to relativistic and nonadiabatic effects.

Contribution

The study provides a highly accurate calculation of the forbidden ortho-para transition rate, incorporating relativistic and nonadiabatic effects, and compares it with prior approximate methods.

Findings

Calculated transition rate: 6.20(62)×10^{-14} yr^{-1}

Transition rate significantly lower than previous estimates

Detection of this weak line in space is currently unlikely

Abstract

The radiative ortho-para transition in the molecular hydrogen is studied. This highly forbidden transition is very sensitive to relativistic and subtle nonadiabatic effects. Our result for the transition rate in the ground vibrational level $\Gamma(J=1\to J=0) = 6.20(62)\cdot 10^{-14} \iyr$ is significantly lower in comparison to all the previous approximate calculations. Experimental detection of such a weak line by observation of, for example, the cold interstellar molecular hydrogen is at present unlikely.