Dynamical resonant charge transfer of fast C−, O−, F− ions and water covered Si(111) surface
| Autor: | Jianjie Lu, Lin Chen, Shunli Qiu, Lei Gao, Ximeng Chen, Yuefeng Liu, Yanling Guo, Xiyu Qiu, Feifei Xiong, Pinyang Liu |
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| Rok vydání: | 2017 |
| Předmět: |
Band gap
Scattering Chemistry Charge (physics) 02 engineering and technology Escape velocity 021001 nanoscience & nanotechnology Condensed Matter Physics 01 natural sciences Surfaces Coatings and Films Ion Exponential function 0103 physical sciences Perpendicular Specular reflection Atomic physics 010306 general physics 0210 nano-technology Instrumentation |
| Zdroj: | Vacuum. 137:23-30 |
| ISSN: | 0042-207X |
| Popis: | The experiment of 6.5-22.5 keV C-, O- and F- ions scattering on water covered Si(111) surface has been performed. It is found that the positive-ion fraction is very low and increases monotonically as a function of perpendicular exit velocity and exit angle. In particular, the negative-ion fraction increases monotonically with perpendicular exit velocity for specular scattering, and for a given incident energy the angle dependence of the fraction is nonmonotonic. We interpret the observed positive ions in terms of inelastic binary collision, and adopt a modified resonant charge transfer model to calculate the bell shaped negative-ion fraction. We find that the neutral yield at short ion-surface distance is nonzero and obeys well an exponential dependence. It strongly indicates that a dynamical equilibrium for negative ion formation is never achieved at short distances, and the band gap effect on charge transfer can be neglected to a large extent in this relatively high energy region. (C) 2016 Elsevier Ltd. All rights reserved. |
| Databáze: | OpenAIRE |
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