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Product preference in O(1D) insertion into CH3D: CH2DOH versus CH3OD

Determine whether O(1D) insertion into CH3D in icy mantles preferentially produces methyl-deuterated methanol (CH2DOH) or hydroxyl-deuterated methanol (CH3OD), and quantify the branching ratios under prestellar conditions.

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Background

Methanol can form via insertion of O(1D) into CH4 following O2 photodissociation, and this pathway may operate with CH3D as the starting molecule.

Understanding whether this route favors CH2DOH or CH3OD is central to interpreting observed deuteration patterns and the CH2DOH/CH3OD ratio.

References

Similar to the formation pathway investigated by , this pathway could also occur starting from CH$_3$D, but it is again unknown if this preferentially forms CH$_2$DOH or CH$_3$OD.

— First Detection of CH3OD in Prestellar Cores (2511.03581 - Kulterer et al., 5 Nov 2025) in Section 5.1 (Origins of Prestellar Methanol Deuterium Fractionation Patterns)