Abstract
The linear-density (number of molecules on an arbitrary distance) of X-ray-induced markedly dense hydroxyl radicals (•OH) in water was estimated based on EPR spin-trapping measurement. A lower (0.13 mM–2.3 M) concentration series of DMPO water solutions and higher (1.7–6.0 M) concentration series of DMPO water solutions plus neat DMPO liquid (8.8 M as DMPO) were irradiated with 32 Gy of X-rays. Then, the yield of DMPO-OH in DMPO water solutions and the total spin-adduct of DMPO in neat DMPO were quantified. For the higher concentration DMPO series, the EPR peak area was estimated by double integration, and the baseline correction of the integral spectrum is necessary for accurate estimation of the peak area. The preparation of a suitable standard sample corresponding to the electric permittivity according to DMPO concentration was quite important for quantification of DMPO-OH, especially in DMPO concentration beyond 2 M. The linear-density of •OH generation in water by X-ray irradiation was estimated from the inflection point on the plot of the DMPO-OH yield versus DMPO linear-density. The linear-density of X-ray-induced markedly dense •OH was estimated as 1168 μm−1, which was converted to 0.86 nm as the intermolecular distance and 2.6 M as the local concentration.
Highlights
Ionizing radiation, even electromagnetic waves or particles, can ionize and/or excite molecules in the material transmitting the ionizing radiation
When the ionizing radiation is traveling through water, the water molecules may be ionized/excited and decomposed to make initial reactive species such as hydroxyl radicals (OH), hydrogen radicals (H), and hydrated electrons (e−aq) [1,2,3,4]
The spur diffusion model is well established as a reaction process of initial reactive species generated by the radiolysis of water [8,9,10,11,12]
Summary
Even electromagnetic waves (photons) or particles, can ionize and/or excite molecules in the material transmitting the ionizing radiation. The spur diffusion model is well established as a reaction process of initial reactive species generated by the radiolysis of water [8,9,10,11,12]. The chemical process of radiolysis of water has been analyzed based on pulse radiolysis. Pulse radiolysis observes the absorbance of target chemical species over time after microsecond or shorter pulsed irradiation, and analyzes the dynamics of the target species. By ionization or excitation of water molecules, some initial reactive species, i.e., ions and radicals, can be generated and distributed in a volume of ~1 nm in diameter, which is termed a “spur” [10]. The reactive species generated in the spur react with each other and diffuse to be uniformly distributed during ~10−6 s [13,14]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
