Abstract
Recent observations toward the low-mass protostars IRAS16293 found the very high D/H ratios in methanol up to 0.4. To date, several models have been proposed to explain D-fractionation mechanism. Pure gas-phase models are difficult to reproduce the D-fractionation, particularly, for multideuterated species. Therefore, we performed the experiments on the formation of deuterated methanol on cold (10 K) interstellar grain analogs and revealed that a key route for the D-fractionation is the H-D substitution in solid CH3OH on icy grains (CH3OH -> CH2DOH -> CHD2OH -> CD3OH).
