ESR spin trapping of radicals in methanol solution irradiated by heavy ion beams. Dependence on specific energy and LET

•The relative yield among radicals produced by ion irradiation of methanol was studied.•The ratio varied depending on the LET value, the specific energy and mass of ions.•The recombination of ionic species will occur effectively for Ar and Fe-ion irradiation.

Radicals produced by the heavy ion (He, C, Ne, Si, Ar, and Fe) irradiation of methanol were spin trapped with PBN. Three kinds of radicals, PBN-CH3O, PBN-CH2OH, and PBN-H, were observed similar to those by γ-irradiation. The relative radical yields, PBN-CH3O/PBN-CH2OH and (PBN-CH3O + PBN-CH2OH)/PBN-H, varied depending on the LET value, the specific energy and mass of ions.