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Secondary electrons
About: Secondary electrons is a research topic. Over the lifetime, 6703 publications have been published within this topic receiving 111977 citations.
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TL;DR: It is shown that reactions of such electrons, even at energies well below ionization thresholds, induce substantial yields of single- and double-strand breaks in DNA, which are caused by rapid decays of transient molecular resonances localized on the DNA's basic components.
Abstract: Most of the energy deposited in cells by ionizing radiation is channeled into the production of abundant free secondary electrons with ballistic energies between 1 and 20 electron volts. Here it is shown that reactions of such electrons, even at energies well below ionization thresholds, induce substantial yields of single- and double-strand breaks in DNA, which are caused by rapid decays of transient molecular resonances localized on the DNA's basic components. This finding presents a fundamental challenge to the traditional notion that genotoxic damage by secondary electrons can only occur at energies above the onset of ionization, or upon solvation when they become a slowly reacting chemical species.
1,756 citations
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TL;DR: Proton beam (p-beam) writing as discussed by the authors is a direct writing process that uses a focused beam of MeV protons to pattern resist material at nanodimensions, which is similar in many ways to direct writing using electrons.
Abstract: Proton beam (p-beam) writing is a new direct-writing process that uses a focused beam of MeV protons to pattern resist material at nanodimensions. The process, although similar in many ways to direct writing using electrons, nevertheless offers some interesting and unique advantages. Protons, being more massive, have deeper penetration in materials while maintaining a straight path, enabling p-beam writing to fabricate three-dimensional, high aspect ratio structures with vertical, smooth sidewalls and low line-edge roughness. Calculations have also indicated that p-beam writing exhibits minimal proximity effects, since the secondary electrons induced in proton/electron collisions have low energy. A further advantage stems from the ability of protons to displace atoms while traversing material, thereby increasing localized damage especially at the end of range. P-beam writing produces resistive patterns at depth in Si, allowing patterning of selective regions with different optical properties as well as the removal of undamaged regions via electrochemical etching.
1,066 citations
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TL;DR: In this paper, the dependence of the yield on the energy just above a threshold is derived and the derivation is not rigorous because it circumvents some of the difficulties of the three-body problem by applying ergodicity, albeit in a weakened form.
Abstract: When an electron hits an atom or ion, it may knock off an electron This process is fundamental in almost all types of gas discharge The reaction is endothermic; hence there is a threshold value in the electron energy below which it does not occur In this paper, the dependence of the yield on the energy just above this threshold is derived The derivation is not rigorous because it circumvents some of the difficulties of the three-body problem by applying ergodicity, albeit in a weakened form The result is that, for atoms, the yield rises as the 1127th power of the energy excess For ions the exponent lies between this number and unity
814 citations