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- ItemThe solvation of electrons by an atmospheric-pressure plasma([London] : Springer Nature, 2015) Rumbach, Paul; Bartels, David M.; Sankaran, R. Mohan; Go, David B.Solvated electrons are typically generated by radiolysis or photoionization of solutes. While plasmas containing free electrons have been brought into contact with liquids in studies dating back centuries, there has been little evidence that electrons are solvated by this approach. Here we report direct measurements of solvated electrons generated by an atmospheric-pressure plasma in contact with the surface of an aqueous solution. The electrons are measured by their optical absorbance using a total internal reflection geometry. The measured absorption spectrum is unexpectedly blue shifted, which is potentially due to the intense electric field in the interfacial Debye layer. We estimate an average penetration depth of 2.5±1.0 nm, indicating that the electrons fully solvate before reacting through second-order recombination. Reactions with various electron scavengers including H + , NO 2- , NO 3- and H 2 O 2 show that the kinetics are similar, but not identical, to those for solvated electrons formed in bulk water by radiolysis.
- ItemEvaluation of monte carlo tools for high energy atmospheric physics(Katlenburg-Lindau : Copernicus, 2016) Rutjes, Casper; Sarria, David; Skeltved, Alexander Broberg; Luque, Alejandro; Diniz, Gabriel; Østgaard, Nikolai; Ebert, UteThe emerging field of high energy atmospheric physics (HEAP) includes terrestrial gamma-ray flashes, electron-positron beams and gamma-ray glows from thunderstorms. Similar emissions of high energy particles occur in pulsed high voltage discharges. Understanding these phenomena requires appropriate models for the interaction of electrons, positrons and photons of up to 40MeV energy with atmospheric air. In this paper, we benchmark the performance of the Monte Carlo codes Geant4, EGS5 and FLUKA developed in other fields of physics and of the custom-made codes GRRR and MC-PEPTITA against each other within the parameter regime relevant for high energy atmospheric physics. We focus on basic tests, namely on the evolution of monoenergetic and directed beams of electrons, positrons and photons with kinetic energies between 100keV and 40MeV through homogeneous air in the absence of electric and magnetic fields, using a low energy cutoff of 50keV. We discuss important differences between the results of the different codes and provide plausible explanations. We also test the computational performance of the codes. The Supplement contains all results, providing a first benchmark for present and future custom-made codes that are more flexible in including electrodynamic interactions.
- ItemComplexes in the Photocatalytic Reaction of CO 2 and H 2O: Theoretical Studies(Basel : Molecular Diversity Preservation International, 2010) Luo, Dongmei; Zhang, Ning; Hong, Sanguo; Wu, Huanwen; Liu, ZhihuaComplexes (H 2O/CO 2, e-(H 2O/CO 2) and h +-(H 2O/CO 2)) in the reaction system of CO 2 photoreduction with H 2O were researched by B3LYP and MP2 methods along with natural bond orbital (NBO) analysis. Geometries of these complexes were optimized and frequencies analysis performed. H 2O/CO 2 captured photo-induced electron and hole produced e-(H 2O/CO 2) and h +-(H 2O/CO 2), respectively. The results revealed that CO 2 and H 2O molecules could be activated by the photo-induced electrons and holes, and each of these complexes possessed two isomers. Due to the effect of photo-induced electrons, the bond length of C=O and H-O were lengthened, while H-O bonds were shortened, influenced by holes. The infrared (IR) adsorption frequencies of these complexes were different from that of CO 2 and H 2O, which might be attributed to the synergistic effect and which could not be captured experimentally. © 2010 by the authors; licensee MDPI, Basel, Switzerland.