| 单词 | positronium |
| 释义 | positronium Nuclear Physics.|pɒzɪˈtrəʊnɪəm|
[f. prec. + -ium.]
A short-lived neutral system, analogous to an atom, consisting of a positron and a negative electron bound together.
1945A. E. Ruark in Physical Rev. LXVIII. 278/1 In 1937 I conceived the idea that an unstable atom composed of a positron and a negative electron may exist in quantities sufficient for spectroscopic detection. The name positronium is suggested. The spectrum of positronium would have lines at wave-lengths twice as great as the hydrogen lines. 1957New Scientist 26 Dec. 28/3 When positronium is in free (i.e., near-vacuum) conditions, spectroscopic measurement shows that it has a lifetime of about one and a half ten-millionths of a second. 1966McGraw-Hill Encycl. Sci. & Technol. X. 524/1 Positronium is of particular interest because it is the two-body system to which quantum electrodynamics is applicable, and its study has served as an important confirmation of the theory of quantum electrodynamics. 1970[see hydrogenic a. b]. 1976Science 19 Nov. 826/3 If ψ were a bound system of two spin ½ particles, there could be excited levels with a spectrum similar to that of positronium (the system of electron and positron, bound to each other by the electromagnetic force). |
英语词典包含277258条英英释义在线翻译词条，基本涵盖了全部常用单词的英英翻译及用法，是英语学习的有利工具。
相关内容11：
相关热词搜索：positronium英英词典英英释义英语词汇意思用法释义英语
字词 高速磁盘 释义 【电】 hyperdisk 汉译英翻译词典收录405719条汉英翻译词条，基本涵盖了全......
字词 高速直流断路器 释义 【电】 high speed d-c circuit breaker 汉译英翻译词典收录405719......
字词 高速离心 释义 【化】 high speed centrifugation 汉译英翻译词典收录405719条汉英翻译词......
单词 sender 释义 sender n person who sends 发送或邮寄物品的人 If undelivered, return to se......
单词 senate 释义 senate n (often 常作 Senate) 1 [CGp] upper house of the law-making assemb......
单词 senescent 释义 senescent adj (fml or medical 文或医) becoming old 衰老的; 变老的. ......