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Toigawa T, Kai T, Kumagai Y, Yokoya A. Consideration of the dielectric response for radiation chemistry simulations. J Chem Phys 2024; 160:214119. [PMID: 38836449 DOI: 10.1063/5.0211089] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2024] [Accepted: 05/15/2024] [Indexed: 06/06/2024] Open
Abstract
The spur reaction, a spatially nonhomogeneous chemical reaction following ionization, is crucial in radiolysis or photolysis in liquids, but the spur expansion process has yet to be elucidated. One reason is the need to understand the role of the dielectric response of the solvating molecules surrounding the charged species generated by ionization. The dielectric response corresponds to the time evolution of the permittivity and might affect the chemical reaction-diffusion of the species in a spur expansion process. This study examined the competitive relationship between reaction-diffusion kinetics and the dielectric response by solving the Debye-Smoluchowski equation while considering the dielectric response. The Coulomb force between the charged species gradually decreases with the dielectric response. Our calculation results found a condition where fast recombination occurs before the dielectric response is complete. Although it has been reported that the primary G-values of free electrons depend on the static dielectric constant under low-linear-energy transfer radiation-induced ionization, we propose that considering the dielectric response can provide a deeper insight into fast recombination reactions under high-linear-energy transfer radiation- or photo-induced ionization. Our simulation method enables the understanding of fast radiation-induced phenomena in liquids.
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Affiliation(s)
- Tomohiro Toigawa
- Nuclear Science and Engineering Center, Japan Atomic Energy Agency, 2-4 Shirakata, Tokai-mura, Naka-gun, Ibaraki 319-1195, Japan
| | - Takeshi Kai
- Nuclear Science and Engineering Center, Japan Atomic Energy Agency, 2-4 Shirakata, Tokai-mura, Naka-gun, Ibaraki 319-1195, Japan
| | - Yuta Kumagai
- Nuclear Science and Engineering Center, Japan Atomic Energy Agency, 2-4 Shirakata, Tokai-mura, Naka-gun, Ibaraki 319-1195, Japan
| | - Akinari Yokoya
- Institute for Quantum Life Science, National Institutes for Quantum Science and Technology, 4-9-1 Anagawa, Inage-ku, Chiba-shi 263-8555, Japan
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Matsuya Y, Yoshii Y, Kusumoto T, Akamatsu K, Hirata Y, Sato T, Kai T. A step-by-step simulation code for estimating yields of water radiolysis species based on electron track-structure mode in the PHITS code. Phys Med Biol 2024; 69:035005. [PMID: 38157551 DOI: 10.1088/1361-6560/ad199b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2023] [Accepted: 12/29/2023] [Indexed: 01/03/2024]
Abstract
Objective. Time-dependent yields of chemical products resulting from water radiolysis play a great role in evaluating DNA damage response after exposure to ionizing radiation. Particle and Heavy Ion Transport code System (PHITS) is a general-purpose Monte Carlo simulation code for radiation transport, which simulates atomic interactions originating from discrete energy levels of ionizations and electronic excitations as well as molecular excitations as physical stages. However, no chemical code for simulating water radiolysis products exists in the PHITS package.Approach.Here, we developed a chemical simulation code dedicated to the PHITS code, hereafter calledPHITS-Chemcode, which enables the calculation of theGvalues of water radiolysis species (•OH, eaq-, H2, H2O2etc) by electron beams.Main results.The estimatedGvalues during 1 μs are in agreement with the experimental ones and other simulations. ThisPHITS-Chemcode also simulates the radiolysis in the presence of OH radical scavengers, such as tris(hydroxymethyl)aminomethane and dimethyl sulfoxide. Thank to this feature, the contributions of direct and indirect effects on DNA damage induction under various scavenging capacities can be analyzed.Significance.This chemical code coupled with PHITS could contribute to elucidating the mechanism of radiation effects by connecting physical, physicochemical, and chemical processes.
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Affiliation(s)
- Yusuke Matsuya
- Nuclear Science and Engineering Center, Research Group for Radiation Transport Analysis, Japan Atomic Energy Agency (JAEA), 2-4 Shirakata, Tokai, Ibaraki, 319-1195, Japan
- Faculty of Health Sciences, Hokkaido University, Kita-12 Nishi-5, Kita-ku, Sapporo, Hokkaido, 060-0812, Japan
| | - Yuji Yoshii
- Department of Radiological Technology, Faculty of Health Sciences, Hokkaido University of Science, Maeda 7-15, Teine-ku, Sapporo 006-8585, Japan
| | - Tamon Kusumoto
- National Institutes for Quantum Science and Technology, 4-9-1 Anagawa, Inage-ku, 263-8555 Chiba, Japan
| | - Ken Akamatsu
- Institute for Quantum life Science, Quantum Life and Medical Science Directorate, National Institutes of Quantum and Radiological Science and Technology (QST), 8-1-7 Umemidai, Kizugawa-shi, Kyoto, 619-0215, Japan
| | - Yuho Hirata
- Nuclear Science and Engineering Center, Research Group for Radiation Transport Analysis, Japan Atomic Energy Agency (JAEA), 2-4 Shirakata, Tokai, Ibaraki, 319-1195, Japan
| | - Tatsuhiko Sato
- Nuclear Science and Engineering Center, Research Group for Radiation Transport Analysis, Japan Atomic Energy Agency (JAEA), 2-4 Shirakata, Tokai, Ibaraki, 319-1195, Japan
| | - Takeshi Kai
- Nuclear Science and Engineering Center, Research Group for Radiation Transport Analysis, Japan Atomic Energy Agency (JAEA), 2-4 Shirakata, Tokai, Ibaraki, 319-1195, Japan
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Kai T, Toigawa T, Matsuya Y, Hirata Y, Tezuka T, Tsuchida H, Yokoya A. First-principles simulation of an ejected electron produced by monochromatic deposition energy to water at the femtosecond order. RSC Adv 2023; 13:32371-32380. [PMID: 37928859 PMCID: PMC10623242 DOI: 10.1039/d3ra05075k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2023] [Accepted: 10/29/2023] [Indexed: 11/07/2023] Open
Abstract
This study uses a time-dependent first-principles simulation code to investigate the transient dynamics of an ejected electron produced in the monochromatic deposition energy from 11 to 19 eV in water. The energy deposition forms a three-body single spur comprising a hydroxyl radical (OH˙), hydronium ion (H3O+), and hydrated electron (eaq-). The earliest formation involves electron thermalization and delocalization dominated by the molecular excitation of water. Our simulation results show that the transient electron dynamics primarily depends on the amount of deposition energy to water; the thermalization time varies from 200 to 500 fs, and the delocalization varies from 3 to 10 nm in this energy range. These features are crucial for determining the earliest single-spur formation and facilitating a sequential simulation from an energy deposition to a chemical reaction in water photolysis or radiolysis. The spur radius obtained from the simulation correlates reasonably with the experimental-based estimations. Our results should provide universalistic insights for analysing ultrafast phenomena dominated by the molecular excitation of water in the femtosecond order.
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Affiliation(s)
- Takeshi Kai
- Nuclear Science and Engineering Center, Japan Atomic Energy Agency 2-4 Shirane Shirakata, Tokai-mura, Naka-gun Ibaraki 319-1195 Japan
| | - Tomohiro Toigawa
- Nuclear Science and Engineering Center, Japan Atomic Energy Agency 2-4 Shirane Shirakata, Tokai-mura, Naka-gun Ibaraki 319-1195 Japan
| | - Yusuke Matsuya
- Nuclear Science and Engineering Center, Japan Atomic Energy Agency 2-4 Shirane Shirakata, Tokai-mura, Naka-gun Ibaraki 319-1195 Japan
- Faculty of Health Sciences, Hokkaido University Kita-12 Nishi-5, Kita-ku Sapporo Hokkaido 060-0812 Japan
| | - Yuho Hirata
- Nuclear Science and Engineering Center, Japan Atomic Energy Agency 2-4 Shirane Shirakata, Tokai-mura, Naka-gun Ibaraki 319-1195 Japan
| | - Tomoya Tezuka
- Department of Nuclear Engineering, Kyoto University Nishikyo-ku Kyoto 615-8530 Japan
| | - Hidetsugu Tsuchida
- Department of Nuclear Engineering, Kyoto University Nishikyo-ku Kyoto 615-8530 Japan
- Quantum Science and Engineering Center, Kyoto University Gokasho, Uji Kyoto 611-0011 Japan
| | - Akinari Yokoya
- Institute for Quantum Life Science, National Institutes for Quantum Science and Technology 4-9-1 Anagawa, Inage-ku Chiba-shi 263-8555 Japan
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