| 摘要 |
<p>PROBLEM TO BE SOLVED: To observe a material of a positive work function to positrons by holding a sample at the incident location of a positron beam, generating an electric field in a pace close to the sample, and accelerating and observing positrons reemitted from the sample. SOLUTION: A sample 10 of a positive work function to positrons held at a sample holding base 3 is irradiated with a positron beam 2 emitted from a positron beam source 1, and an electron lens 5 and screen 7 are arranged on the downstream side of the sample 10. The sample 10 is brought into a high potential side by a high voltage power source 8 to generate an electric field toward the screen 7. Then when the electric field is strengthened, an apparent work function is reduced and a distance is shortened. A potential barrier in the vicinity of the surfaces of the sample 10 is lowered and thinned when viewed from the positrons, and positrons 4 inside the sample 10 are reemitted by the tunnel effect when the potential barrier is thinned. As a beam of the reemitted positrons 4 is enlarged and projected onto the screen 7 by the electron lens 5, it becomes possible to obtain information on impurities, etc., in the surfaces from the projected images.</p> |
