| 摘要 |
A device for determining the kinetic energy of ions scattered from a surface of a target body by a primary ion beam impinging on the surface, in accordance with the LEIS technique. Backscattered ions are separated by an electrostatic energy analyzer relative to their kinetic energy and are detected by a detector. A signal processing device, connected to the detection device, processes data provided by the detection device with respect to the number of detected ions relative to their energy. When measuring the energy spectrum of backscattered ions, in practice, a strong background signal occurs from ions sputtered from the target body surface. According to the invention, a time window/time-of-flight analysis is performed on ions reaching the detection device, based thereon that ions sputtered from the target body surface generally have a mass which signficantly differs from the mass of the ions of the primary ion beam impinging on the target body surface, and in that these sputtered ions with more or less the same kinetic energy as the backscattered ions, have greatly different propagation times, seen from the target body surface towards the detection device. By processing, during the measurement, only those ions of which the path/time-of-flight of the target body surface to the detection device is within a broad time window at the detection device, a disturbing influence by sputtered ions on the processed energy spectrum of the backscattered ions of the primary ion beam, the so-called background, is suppressed. Due to large differences in mass between sputtered ions and ions of the primary ion beam, a coarse and relative wide setting of the time window suffices. |
