Calculation and comparative analysis of the mean energy expended per ion pair by electrons in water and hydroxyl radical

Abstract

Researches of physical and chemical processes occurring in water during the interaction with particles (electrons, ions, photons, etc.) are interesting for a wide range of physical and applied problems in astrophysics, radiation physics, chemistry, medicine and biology, plasma physics, and other branches of science and technology. One of the directions, which invokes a considerable interest in low-temperature plasma physics and its application technologies, includes researches of electric discharges in the liquid and above its surface. While developing any technology, in which electric discharges in a liquid and above its surface will be used, the determination of the main channels of energy expenditure and, accordingly, the total amount of energy expenditure comprises an important task. One of the main channels of energy expenditures are those for ionization by an electron impact, or the so-called ionization cost W. The cost of ionization by an electron impact is usually assumed to be a certain mean value of energy spent by an electron for the formation of an ion-electron pair in the substance.The paper presents the results of calculations and comparison of the cost of ionization of water and hydroxyl radical by an electron impact on the basis of two models. The calculations based on the model with the passage of a monoenergetic electron flow (beam) with an energy of 14-1000 eV through the medium show that for an electron energy of 1000 eV, the ionization cost for the water molecule is W = 25.26 eV and W = 21.65 eV for the hydroxyl radical. The results of calculations show that the ionization cost for the model taking into account the electron energy distribution function in a plasma with T e = 100 eV, this value is W = 16.85 eV for the water molecule and W = 14.5 eV for the hydroxyl radical.

A Comprehensive Analysis of the Relationship Between Dose Rate and Biological Effects in Preclinical and Clinical Studies, From Brachytherapy to Flattening Filter Free Radiation Therapy and FLASH Irradiation

“…We also assumed that the mean energy expended in water per ionization is W ¼ 30 eV according to ovtun 10 and Ardaillou. 11 Given the number of cells and particles involved all spatial quantities could be averaged.…”