--- title: "从沟道射线的颜色读出原子的运动" description: "迎面飞来和背离飞去的氢原子，为什么发出不同颜色的光？" canonical_url: "https://sandboxphysics.com/zh/stories/quantum-evidence/stark-canal-rays-doppler-emitters/" language: "zh-CN" page_type: "story" alternate_languages: en: "https://sandboxphysics.com/stories/quantum-evidence/stark-canal-rays-doppler-emitters/" last_modified: "2026-10-24" --- [量子物理：读懂证据](https://sandboxphysics.com/zh/stories/quantum-evidence/) 诺奖 A · 证据与操控 # 从沟道射线的颜色读出原子的运动 Sandbox Physics · 2026-10-15 迎面飞来和背离飞去的氢原子，为什么发出不同颜色的光？ ## 阴极背后出现一束光 低压气体放电时，带正电的粒子向阴极加速。阴极上开一些小孔，部分粒子便穿过去，在背后形成束流，这就是沟道射线。Stark 研究这束运动的气体发出什么光，1905 年在氢谱中看到了随观察方向而变的位移。 1919 年的颁奖辞描述：原来的氢谱线旁边，多出一个较宽的分量。发光者迎面而来，分量向短波移动；背离观察者飞去，就向长波移动。这个随方向翻转的变化，正是运动在光谱上留下的记号。 证据阅读：J. Stark (1919), Structural and Spectral Changes of Chemical Atoms — Nobel lecture and 1919 presentation speech, Columbia-hosted volume, PDF pp. 160–172 ## 像听到驶过的汽笛 列车驶来时，接连的声波更快到达耳朵，音调偏高；驶离时音调变低。光也有多普勒效应。发光原子朝观察者运动，收到的光频率偏高，波长变短；原子远离，波长变长。 下式适用于速度远小于光速的情形。参考波长是同一跃迁在原子静止时的波长，观测波长与它相比发生了位移；视线速度约定为远离观察者时取正，c 是光速。沿束流两头观察，位移会反号；从侧面观察，一阶视线位移消失。 $$ \frac{\lambda_{\mathrm{obs}}-\lambda_0}{\lambda_0}\simeq\frac{v_{\mathrm{los}}}{c} $$ 证据阅读：J. Stark (1919), Structural and Spectral Changes of Chemical Atoms — Nobel lecture and 1919 presentation speech, Columbia-hosted volume, PDF pp. 160–172 NIST Atomic Spectroscopy, Spectral Line Shapes, Widths, and Shifts — Doppler and pressure broadening ## 束流的名字没有告诉我们谁在发光 这给 Stark 留下了另一个问题：带电粒子经电场加速以后，到发光时还带电吗？粒子穿过气体会碰撞，也可能交换电子。束流中可以同时有离子和快速的中性原子。光谱的多普勒位移告诉人们发光者在动，要辨认它的电荷，还需要别的证据。 Stark 在诺奖讲稿里讨论了中性射线给早期解释带来的困难。按今天的归属，可见的氢 Balmer 谱线来自仍有一个电子的中性氢。这个电子在不同能级之间跃迁，才发出那些颜色；裸质子没有这样的电子能级。 证据阅读：J. Stark (1919), Structural and Spectral Changes of Chemical Atoms — Nobel lecture and 1919 presentation speech, Columbia-hosted volume, PDF pp. 160–172 NIST Handbook, Strong Lines of Hydrogen — H I visible Balmer wavelengths ## 一束原子为什么画成一条宽带 束流里的原子通常有快有慢，各自的多普勒位移不同，叠起来便是一条宽线。粒子定向运动会移动线心，随机热运动会增加宽度，碰撞和光谱仪本身又会添上展宽。想从宽度求温度，得先知道这些贡献分别占了多少。 这也解释了为什么要换观察方向、保留未移位的参考线并标定仪器。从侧面看虽能去掉一阶视线位移，其他展宽和更高阶运动效应仍会留下。 Stark 后来发现的电场分裂改变的是原子内部能量；多普勒位移跟着原子与观察者的相对运动走。同一根放电管里两者可以并存。分别改变电场和观察方向，才有机会读清它们各自留下的线索。 证据阅读：NIST Atomic Spectroscopy, Spectral Line Shapes, Widths, and Shifts — Doppler and pressure broadening J. Stark (1919), Structural and Spectral Changes of Chemical Atoms — Nobel lecture and 1919 presentation speech, Columbia-hosted volume, PDF pp. 160–172 ## 接着操作模型 下面这些教学 Lab 产生的是模拟数据，和上文讨论的历史观测不是一回事。 - [数运动和静止氢原子发出的模拟光子](https://sandboxphysics.com/zh/labs/canal-ray-doppler-spectrometer/) - [对照电场怎样移动原子能级](https://sandboxphysics.com/zh/labs/stark-splitting-spectrometer/) ## 来源与阅读说明 Stark 1919 年的讲稿和颁奖辞取自 Columbia 托管的诺奖文集，讲稿谈到了中性粒子，以及究竟是谁在发光的争议。现代谱线展宽的背景依据 NIST。文中认为离子发光的说法只作为历史观点介绍，不是今天对氢 Balmer 发射的归属。本文没有数字化任何历史底片。 1. [J. Stark (1919), Structural and Spectral Changes of Chemical Atoms — Nobel lecture and 1919 presentation speech, Columbia-hosted volume, PDF pp. 160–172](https://www.nevis.columbia.edu/~haas/documents/physics_nobel_lectures/physics01-21-2.pdf) 2. [NIST Atomic Spectroscopy, Spectral Line Shapes, Widths, and Shifts — Doppler and pressure broadening](https://physics.nist.gov/Pubs/AtSpec/node20.html) 3. 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