NATURAL ORTHO-PARA CONVERSION RATE IN LIQUID AND GASEOUS-HYDROGEN

We measured natural ortho-para conversion rates within a wide region o f hydrogen fluid stares: at temperatures 17-32 K in the liquid ann at temperatures 40-120 K in the gas for densities trp to 0.09 g/cm(3). Th e experimental data for the gas phase ale interpreted within the frame work of a theory, the basic distinction of which from Wigner's approa ch is that we take into account the dependence of the closest distance in a collision of two orthomolecules on their velocity (i.e., tempera ture). Our theory yields results in good qualitative agreement with ex periment in the gas phase. In order to describe the entire bulk of con version rate data in the hydrogen fluid phases we suggest a convenient interpolation formula, which has reasonable physcial grounds.