What term describes the process where photons from spontaneously decaying electrons strike other excited electrons?

The process where photons from spontaneously decaying electrons strike other excited electrons is known as stimulated decay. In this context, stimulated decay refers to the interaction where an incoming photon prompts an excited electron to transition to a lower energy state, resulting in the emission of an additional photon. This emitted photon is coherent with the incoming photon, meaning it has the same phase, frequency, and direction. It is a key principle in laser operation, where the stimulated emission of photons leads to the amplification of light and the generation of a coherent laser beam.

In contrast, spontaneous decay refers to a natural occurrence where an excited electron transitions back to a lower energy state without any external influence, resulting in the emission of a photon in a random direction and phase. Electron excitation describes the process of an electron absorbing energy and moving to a higher energy state, rather than the subsequent interactions involving photons. Photon interaction is a broader term that does not specifically define the process of stimulated decay, as it could encompass various types of interactions between photons and matter. Therefore, the term stimulated decay accurately captures the described process in the question.