IRRADIATION OF DUST IN MOLECULAR CLOUDS. II. DOSES PRODUCED BY COSMIC RAYS

The fluxes of cosmic rays inside typical molecular clouds are calculated. Protons and a-particles with energies of 1 MeVd <= angstrom <= 10 GeV penetrate deeply enough to produce irradiation doses in the ice mantle of dust particles on the order of 0.1-1 eV/amu over the 10-50 million year lifetime of clouds with and without star formation regions. The possible use of these results for interpreting laboratory experiments on the irradiation of ice mixtures of the type H(2)O:CH(3)OH:NH(3):CO is discussed. Complex organic radiolysis products may play an important role in the prebiological evolution of the dust component of molecular clouds.