Is it possible for an atom to absorb two photons and then emit one photon?

When two atoms are placed in a small chamber enclosed by mirrors, they can simultaneously absorb a single photon. So says an international team of researchers, which has found that the reverse process – two excited atoms emitting a single photon – is also possible.

Why can’t an electron absorb a photon?

A free electron cannot absorb a photon as it is not possible to satisfy the energy and momentum conservation simultaneously. Consider a photon with energy and momentum being absorbed by an electron at rest (hence having zero initial momentum and rest mass energy .

How an electron absorb a photon?

Photon absorption by an atomic electron occurs in the photoelectric effect process, in which the photon loses its entire energy to an atomic electron which is in turn liberated from the atom. This process requires the incident photon to have an energy greater than the binding energy of an orbital electron.

Why does an electron emit a photon?

When the electron changes levels, it decreases energy and the atom emits photons. The photon is emitted with the electron moving from a higher energy level to a lower energy level. The energy of the photon is the exact energy that is lost by the electron moving to its lower energy level.

How many photon are needed to eject an electron?

Once the energy of a photon is higher than the bonding energy, one photon is enough to eject that electron.

How many photons are needed to remove an electron?

Typically, one photon is either energetic enough to cause emission of an electron or the energy is lost as the atom returns back to the ground state.

What is single photon absorption?

Single-photon absorption (SPA or 1PA) is a linear absorption process whereby one photon excites an atom, ion or molecule from a lower energy level to a higher energy level, for example, from the ground state to the first excited state.

What happens when an electron releases a photon?