英语听力文摘 English Digest 572、神奇的发光色彩？

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　　Have you ever wondered why fluorescent¹ colors, like you see in highlighters or clothing dyes, for instance,seem so much brighter than other colors?

 

　　It’s because they seem to reflect more light than they receive! It may sound like a magic trick, but it makes sense if you think about the fact that the light you can see is only a small section of the larger spectrum² of energy all around you.

 

　　Regular, non-fluorescent colors appear to our eyes when objects absorb some wavelengths⁴ of light, and reflect others. For example, a yellow pencil looks yellow because its paint reflects the wavelength³ of yellow light, and absorbs the other wavelengths. Fluorescent colors also reflect or absorb colors in the visible spectrum, but that extra glow in fluorescent colors comes from energy we humans don’t see,ultraviolet light.

 

　　Ultraviolet light, or UV, is just beyond visible violet in the spectrum. Its wavelength is too short to be visible to the naked eye, but you see it working when fluorescent colors glow! Regular dyes just absorb UV along with all the other wavelengths they don’t reflect, so you don’t see any evidence of it.

 

　　But, fluorescent dyes contain substances that respond to UV. Some of the molecules⁵ in these fluorescent dyes are excited by UV energy, and afterwards, as the energy level within these molecules decreases, they release part of that extra energy as visible light.

 

　　So fluorescent dyes turn invisible energy into visible light, and that’s how the magic trick works! They don’t reflect more energy than they receive, but they do reflect more visible light, converted from parts of the spectrum we can’t see.

 

　　神奇的发光色彩？

 

　　你想知道为什么荧光色，譬如你从荧光笔或服装染料上看到的颜色，似乎比别的颜色更鲜亮吗？

 

　　原因是这些颜色反射的光线比吸收的光线要多。这可能听起来像个魔术，但是如果你想到这样一个事实，即可见光只是你周围更大光谱能量中的一小部分，那这就合理了。

 

　　当物体吸收一些波段的光并反射其他光，我们就能看见一般的非荧光色。例如，黄色彩笔之所以看起来是黄色是因为该种颜料反射黄色光波，并且吸收其他波段的光。荧光色也反射或吸收了光谱中的可见光，但是荧光色额外的光来自于人眼看不到的能量，紫外光。

 

　　紫外光，或称作UV，频率恰好在可见紫光之外。紫外光的波长太短以至于无法用肉眼看到，但是荧光色发光的时候你就能看到它起的效果！一般的染料只是吸收紫外光和所有其他不反射的光，所以你看不到紫外光的存在。

 

　　但是，荧光染料含有对UV起反应的物质。这些荧光染料中的一些分子被UV的能量激活，然后随着这些分子的能量水平降低，它们就会以可见光的形式释放出一部分额外的能量。

 

　　所以荧光染料把不可见的能量转换成了可见光，这就是魔术的奥妙所在！不是它们反射出的能量比接收的多，而是反射出了更多的可见光，这些多出来的可见光是从我们看不到的波段转换来的。

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