Significance: A significant amount of radical related luminescence is observed from the titanium dioxide (TiO2) plate during irradiation of alpha particles although alpha particles do not emit Cerenkov-light. Aim: TiO2 is a promising material for application to photodynamic therapy in combination with positron radionuclides that emit Cerenkov light. However, it is not clear that radicals are produced by the irradiation of alpha particles, since although Cerenkov light is required to produce radicals, alpha particles do not produce Cerenkov light. Approach: To clarify this point, the author irradiates alpha particles to a TiO2 plate and measured the produced luminescence of the plate, which indicates the radical production in TiO2. Results: A significant amount of luminescence was observed from the TiO2 plate during irradiation of alpha particles. The spectrum of luminescence from the TiO2 plate during this irradiation was the same as that emitted by ultraviolet (UV) light irradiated luminescence, which actually showed radical production in a TiO2 plate. This luminescence was not attributed to the UV light from the air scintillation by alpha particles but to the direct irradiation of alpha particles to the TiO2 plate. Conclusions: A significant amount of luminescence from TiO2 plate was detected during irradiation of alpha particles. The luminescence is thought to be emitted from the radicals produced by the direct alpha particle irradiation to the TiO2 plate.

中文翻译：

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在 α 粒子辐照期间检测 TiO2 板中自由基的发光。

意义：尽管 α 粒子不发射切伦科夫光，但在 α 粒子辐照期间从二氧化钛 (TiO2) 板上观察到大量与自由基相关的发光。目标：TiO2 是一种很有前景的材料，可与发出切伦科夫光的正电子放射性核素结合应用于光动力疗法。然而，自由基是否由α粒子的照射产生尚不清楚，因为虽然产生自由基需要切伦科夫光，但α粒子不产生切伦科夫光。方法：为了澄清这一点，作者将α粒子照射到TiO2板上并测量板产生的发光，这表明TiO2中的自由基产生。结果：在α粒子辐照期间，从TiO2板观察到大量发光。在此照射过程中，TiO2 板的发光光谱与紫外 (UV) 光照射的发光所发出的光谱相同，这实际上表明在 TiO2 板中产生了自由基。这种发光不是由于 α 粒子在空气中闪烁产生的紫外光，而是由于 α 粒子直接照射到 TiO2 板上。结论：在α粒子辐照期间检测到大量来自TiO2板的发光。发光被认为是由α粒子直接照射到TiO2板上产生的自由基发出的。这种发光不是由于 α 粒子在空气中闪烁产生的紫外光，而是由于 α 粒子直接照射到 TiO2 板上。结论：在α粒子辐照期间检测到大量来自TiO2板的发光。发光被认为是由α粒子直接照射到TiO2板上产生的自由基发出的。这种发光不是由于 α 粒子在空气中闪烁产生的紫外光，而是由于 α 粒子直接照射到 TiO2 板上。结论：在α粒子辐照期间检测到大量来自TiO2板的发光。发光被认为是由α粒子直接照射到TiO2板上产生的自由基发出的。