Absorption is just the opposite of emission, so instead of starting at a high energy level and dropping down, when we absorb light we start low and we absorb energy to bring ourselves up to an n final that's higher.

吸收就是发射的逆过程,与从一个高能量到低能量不同，当吸收光时，我们从低能量开始,吸收能量到一个更高的能量。

麻省理工公开课 - 化学原理课程节选

we start high and go low, we're dealing with emission where we have excess energy that the electron's giving off, and that energy is going to be equal the energy of the photon that is released and, of course, through our equations we know how to get from energy to frequency or to wavelength of the photon.

当我们从高到低时，我们说的,是发射,电子有多余的能量给出，这个能量等于，发出,光子的能量，当然我们可以通过方程,从能量知道，光子的频率，和波长。

麻省理工公开课 - 化学原理课程节选