Hydrogen molecules trapped in irradiated solid ethanol

Raman spectroscopy of γ-irradiated solid ethanol at 77 K revealed that trapped H₂ is produced mainly by the H atom abstraction at the alkyl group by H radicals which are dissociated from the alkyl group of ethanol. Comparison of the peak wavenumbers and the band widths of H₂ between the glassy and crystalline phases of ethanol suggests that the trapping sites of H₂ in the glassy phase are smaller in the average size and less homogeneous in the size distribution. The molar ratio between ortho- and para-H₂ trapped in irradiated crystalline ethanol is in rough agreement with the thermodynamic equilibrium between 5–120 K, intimating that the ortho-para conversion is allowed under the existence of an electro-magnetic gradient due to paramagnetic radicals.