| 摘要 |
1. Device for the observation of electrons scattered at a specimen for investigating crystal surfaces according to the LEED technique, comprising an electron source, means for visualizing the scattered electrons and an electron-optical device which is mounted directly in front of the specimen and through which both the primary electrons and the scattered electrons pass, characterized in that the electron-optical device is a lens (8) which comprises at least two annular diaphragms (13, 14 or 16, 17, 18), of which the electrode (14, 18) adjacent to the specimen is at earth potential, in order to keep the specimen almost fieldfree. |
