@article{oai:repo.qst.go.jp:00085018,
 author = {牧野, 祐典 and 上野, 恵美 and 中西, 郁夫 and 松本, 謙一郎 and Yusuke, Makino and Megumi, Ueno and Ikuo, Nakanishi and Kenichiro, Matsumoto},
 journal = {2020年度量子医科学研究所重粒子線がん治療装置等共同利用研究報告書​},
 month = {Nov},
 note = {Hydrogen radicals (•H) generated during irradiating to aqueous solutions were quantified by an electron paramagnetic resonance (EPR) spin-trapping technique using a spin-trapping agent, 5,5-dimethyl-1-pyrroline-N-oxide (DMPO). The •H could be generated by reaction of hydrated electron (eaq) and hydrogen ions (H+), which were generated simultaneously with hydroxyl radical (•OH) from ionized water (H2O+). Therefore, the local density of •H may be the similar amounts of •OH.
A concentration series of DMPO aqueous solutions (0.49 mM 〜 1700 mM) was prepared. The sample solutions were irradiated 32 Gy of 20 keV/μm, or 80 keV/μm carbon-ion beam. Signal intensities of DMPO-H caused in the sample were measured by X-band EPR spectrometer. The profiles observed by plotting concentrations of DMPO-H against the DMPO density (reciprocal of the intermolecular distance of DMPO) were analyzed.
When X-ray or carbon-ion beam was irradiated to DMPO aqueous solutions under aerobic condition, the profile of DMPO-H generation showed 2-phase and have an inflection point at 160 µm-1 or 125 µm-1, respectively. The intermolecular distance of •H generated by X-ray or carbon-ion-beam in water was estimated as 6.3 or 8.0 nm, respectively. Under hypoxic condition, DMPO-H generation profile showed plateau over the DMPO density more than 100 µm-1 and the molecular distance of •H was estimated as 10 nm for either X-ray or carbon-ion beam irradiation.},
 pages = {160--161},
 title = {重粒子線が水溶液中で生成する水素ラジカルの定量},
 year = {2021}
}