The spontaneous emission phenomenon of an excited atom is one of basic processes in quantum optics.

激发态原子的自发辐射现象是量子光学领域是最基本的过程之一。

Both interactions of a two-level atom with a vacuum field and a excited atom with a coherent field, as examples, are discussed in detail.

作为例子，详细讨论了二能级原子与真空场的相互作用以及处于激发态的原子与相干场的相互作用。

When they breakthrough, they collide with atoms and molecules, which take some of the energy and store it, creating what's known as an excited atom.

冲破大气层过程中，这些高能粒子与高层大气的原子或分子碰撞，促使这些原子或分子吸收一部分的能量并将其储存，产生一种所谓的激发态原子。