主题：【讨论】金(Au)为什么是黄色，银(Ag)为什么是白色？

不知哪位版友做过Cu,Ag,Au的分光，呵呵？

原文由 大陆(handsomeland) 发表:
不知哪位版友做过Cu,Ag,Au的分光，呵呵？

测钢铁里的cu，显色是绿色的

原文由 冬季(lylsg555) 发表:
测钢铁里的cu，显色是绿色的

钢铁显色需要经过腐蚀吧？这和纯金属不是一回事。

原文由 冬季(lylsg555) 发表:

原文由 大陆(handsomeland) 发表:
不知哪位版友做过Cu,Ag,Au的分光，呵呵？

测钢铁里的cu，显色是绿色的

我记得是黄的

纯铜是红色。黄铜是CuZn合金。

其实本人对颜色如何产生并没有什么研究，只是工作需要经常接触有关颜色材料，也会看一些有关颜色方面的资料，但也只是了解一些浅显而宏观的说法，并不对一些颜色成因的基础理论有过深入的研读。

看到大陆朋友这方面兴趣，也来凑个热闹；因为上面大陆所设的链接打不开，无法看其究竟，查了颜色科学的有关内容，有关大陆版友金属颜色问题的一些原则性说法如下，其原理性解释角度似乎与上述大陆说的“吸收”稍有些不同，摘了一些供参考：

    When light falls onto a metal, the electrons below the Fermi surface can also become excited into higher energy 

levels in the empty part of the band by absorbing the energy from the light, producing electron-hole pairs....... 

The light is so intensely absorbed that it can penetrate to a depth of only a few hundred atoms, typically less than

a single wavelength. Since the metal is a conductor of electricity, this absorbed light which is, after all, an

electromagnetic wave, will induce alternating electrical currents in the metal surface. Electromagnetic theory shows

that these currents immediately re-emit the light back out of the metal, thus providing the strong reflection of a

smooth (polished) metal surface.

    The efficiency of this process depends on the selection rules which apply to the atomic orbitals from which the

energy band had formed. If the efficiency of the absorption and re-emission processes is approximately equal at all

optical energies, then the different wavelengths present in white light will be reflected equally well, thus leading

to the silvery colors of the smooth surfaces of metals such as iron, chromium, and silver. However, if the

efficiency decreases with increasing energy, as is the case for gold and copper, the slightly reduced reflectivity

at the higher energy end of the spectrum results in the observed yellow and reddish colors, respectively. The colors

of alloys follow the same general pattern but are difficult to predict. For example, the addition of 25% copper to

pure gold produces an alloy with a reddish color, while a similar amount of silver produces a greenish one.

  The direct light absorption of a metal in the absence of reflection can be observed only rarely. Gold is

extremely malleable and can be beaten into gold leaf less than 100 nm thick. This is less than the thickness

necessary to support fully the electric currents which produce the metallic reflection. Under these circumstances a

bluish green color is additionally seen in transmitted light. When gold is in a colloidal form, however as in the 10

nm diameter particles which give the color to ‘ruby glass,’ the complex scattering theory originated by Mie

explains the unexpected red color. A yellow color in glass also derives from Mie scattering, but here from metallic

colloidal silver particles. Both of these colors can be seen in Figure 7.26

（http://bbs.instrument.com.cn/shtml/20100716/2666982/）.

不知道上面发的贴为什么不能编辑了，总是出现“非法字符”的字样，只能剪贴个图放上，不然大家要看不明白了。

多谢tutm老师的有益纠正和补充。
对于金属材料，因为自由电子对电磁波的反射是非常重要的，仅仅用“吸收”囊括确实容易误导读者。

这样的深入研究产生的理论才能指导和推动科技重大发展

原文由 tutm(tutm) 发表:
这样的深入研究产生的理论才能指导和推动科技重大发展

受教了，感谢tutm