New channel in ortho-para hydrogen conversion.

Abstract

A new channel in ortho-para hydrogen conversion is suggested as a tentative interpretation of large experimental reaction rates. This process occurs in two steps, via a virtually excited electronic state. The first step involves an exchange of electrons between the molecule and a nearby magnetic impurity while the second step is due to the hyperfine contact interaction between the virtually excited electronic spin of the molecule and its nuclear spins. This new process turns out to be more effective than the Wigner one if the exchange interaction exceeds a moderate value.