用激光照射氢原子或反氢原子，观察何种波长的光线被吸收了，可以通过这种办法来详细地比较这两种原子的能级。

By shining laser light onto hydrogen or antihydrogen and observing which wavelengths are absorbed, the energy levels of the two can be compared in detail.

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通过紫外线光电子光谱和光学吸收的测量，研究人员测定了纳米晶体中电子的最低激发态能级。

By using UV photoelectron spectroscopy and optical absorption measurements, the researchers determined the energy of the lowest excited electronic states in the nanocrystals.

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当这些能级中，发生电子跃迁时，这些电子便吸收并释放出不同特定频率的光。

When electrons jump between these energy levels, they absorb and emit light of particular frequencies.

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We start at this lower energy state and go up that means we need to absorb a photon, we have to take in energy.

我们从一个低能级开始，到一个高能级去,这意味着需要吸收一个光子，我们要获得能量。

麻省理工公开课 - 化学原理课程节选

And what we predict as an energy difference between two levels, we know should correspond to the energy of light that's either emitted, if we're giving off a photon, or that's absorbed if we're going to take on a photon and jump from a lower to a higher energy level.

我们预测，两个能级之间的能量差，我们知道，它要么和发出的光有关,如果它发出光子的话，要么它吸收光子,从低能级跃迁到，更高能级上去。

麻省理工公开课 - 化学原理课程节选