What is released in the process of an atom decaying from an excited level to a lower energy level?

When an atom decays from an excited energy level to a lower energy level, it releases energy in the form of a photon. This process is known as emission. The photon carries away the energy difference between the higher and lower energy levels. The energy of the emitted photon is related to the specific energy levels involved in the transition, and the wavelength (or frequency) of the emitted light corresponds to the energy of the photon according to the equation

E = h⋅f,

where ,

E is the energy,

h is Planck's constant, and

f is the frequency of the emitted light.

This phenomenon is often observed in atomic or molecular systems, where electrons absorb energy to move to higher energy levels and then release energy as they return to lower energy levels, emitting light in the process. The emitted light can be in the visible range or other parts of the electromagnetic spectrum, depending on the specific transition.