当光子照射到材料表面时，电子受到光子的激发由一个能级跳到更高的能级上，而这些能级对材料来说是特定的。

When a photon strikes the surface, it excites an electron to a higher energy level, which is specific to the material.

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也就是说，常温会，激发分子的一些转动能级。

In other words, ordinary thermal energies do populate some number of rotational levels of molecules.

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这种获得能量的电子和他留在原来能级上对应的位置的空穴的相互作用叫做一个激子激发过程，而这两个不同能级之间的部分被称作带隙。

The interaction between the energized electron and the hole it leaves behind is called an exciton, and the difference in energy levels between the hole and the electron is known as the bandgap.

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So, if you use a black lamp or something and you excite something up to a higher energy level and then it relaxes back down to its lower energy state, it's going to emit a new wavelength of light, which is going to be visible to you.

如果你用一个紫外灯或别的,东西把某种分子激发到,更高的能级，然后它会掉回,到低能级，它就会释放,一个新的波长的光,这个光是可见的。

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