@article{oai:repo.qst.go.jp:00082660,
 author = {Ken-ichiro, Matsumoto and Ueno, Megumi and Nyui, Minako and Shoji, Yoshimi and Nakanishi, Ikuo and Kenichiro, Matsumoto and Megumi, Ueno and Minako, Nyui and Yoshimi, Shoji and Ikuo, Nakanishi},
 issue = {6},
 journal = {Free Radical Research},
 month = {Sep},
 note = {Linear energy transfer (LET) dependence of yields of O2-dependent and O2-independent hydrogen peroxide (H2O2) in water irradiated by ionizing radiation was investigated. The radiation-induced hydroxyl radical (•OH) generation in an aqueous solution was reported to occur in two different localization densities, the milli-molar (relatively sparse) and/or molar (super-dense) levels. In the milli-molar-level •OH generation atmosphere, •OH generated at a molecular distance of ~7 nm are likely unable to interact. However, in the molar-level •OH generation atmosphere, several •OH were generated with a molecular distance of 1 nm or less, and two •OH can react to directly make H2O2.
An aliquot of ultra-pure water was irradiated by 290-MeV/nucleon carbon-ion beams at the Heavy-Ion Medical Accelerator in Chiba (HIMAC, NIRS/QST, Chiba, Japan). Irradiation experiments were performed under aerobic or hypoxic (<0.5% oxygen) conditions, and several LET conditions (13, 20, 40, 60, 80, or >100 keV/μm). H2O2 generation in irradiated samples was estimated by three methods. The amount of H2O2 generated per dose was estimated and compared.
O2-independent H2O2 generation, i.e. H2O2 generation under hypoxic conditions, increased with increasing LET. On the other hand, the O2-dependent H2O2 generation, i.e. subtraction of H2O2 generation under hypoxic conditions from H2O2 generation under aerobic conditions, decreased with increasing LET. This suggests that the super-dense •OH generation is positively correlated with LET. High-LET beams generate H2O2 in an oxygen-independent manner.},
 pages = {589--594},
 title = {Effects of LET on oxygen-dependent and-independent generation of hydrogen peroxide in water irradiated by carbon-ion beams},
 volume = {55},
 year = {2021}
}