What occurs when a photon strikes an excited atom?

When a photon strikes an excited atom, the primary interaction that can occur is the absorption of the photon, leading to an energy gain for the atom. In this scenario, an atom that is already in an excited state can absorb the photon, which may further increase its energy level or, in some cases, lead to a specific emission process.

When the photon is absorbed by an excited atom, it typically results in changes to the electronic states of the atom, which can lead to a new photon being emitted. This newly emitted photon can have the same energy—and therefore the same wavelength—as the absorbed photon, but it is not an identical emission of the original photon struck; rather, it is a result of the atom returning to a lower energy state after being excited further.

In general, processes such as emission or absorption are governed by quantum mechanics, where the probabilities of states and transitions are key. The other options imply either a net loss of energy or different interactions that do not consistently align with how photons and excited atoms typically interact.