FTIR study of nuclear spin conversion of solid normal hydrogen at 4.2 K, doped with H2O, CH3F, CH4 and double doped with O2. Evidence of ortho-H2 catalyzed conversion by CH3F

From the IR induced spectrum between 4000 and 5000 cm−1 of solid normal hydrogen doped with H2O, CH3F, CH4, and double doped with O2, the nuclear spin conversion of ortho-H2 molecules has been analyzed at 4.2 K. The self-conversion rate is determined to be Ksc = 2.8(3) × 10−4 min−1, with no implication of O2 atmospheric impurity. Within the framework of an ortho-H2 diffusion dominated process, the O2 catalyzed conversion rate is deduced to be Kcc = 0.17(3) min−1. We have shown that CH3F induces ortho-H2 conversion at the same rate as O2, according to a diffusion controlled process, via intra-cluster conversion.