Radiation-induced radicals in different polymorphic modifications of d-mannitol: Structure, conformations and dosimetric implications

• Radicals in irradiated d-mannitol were characterized by EPR.
• Effect of molecular packing on radical conformations was studied.
• Applications of d-mannitol as a prospective EPR dosimeter are discussed.

The structure and conformation of radicals produced by X-ray irradiation of three polymorphic forms of d-mannitol were investigated using EPR spectroscopy. In all the cases, primary species were identified as radicals resulting from hydrogen abstraction from position 3 or 4 of the mannitol molecule. It was found that molecular packing in crystals of different polymorphic modifications had noticeable effect on the conformation of radicals observed after irradiation at room temperature and the dehydration of the primary radicals occurring at 400 K. The radicals trapped in stable modifications (β- and δ-forms) were found to be very stable at room temperature. Relatively high radical yields and remarkable stability of radicals suggest that d-mannitol can be used as an EPR dosimeter or irradiation marker.