SPONTANEOUS EMISSION Meaning and
Definition
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Spontaneous emission is a phenomenon in physics that refers to the spontaneous emission of electromagnetic radiation by an atom or molecule in an excited state. When an atom or molecule absorbs energy and transitions to an excited state, it can release this excess energy in the form of a photon without any external assistance. This emission occurs randomly in time and in all directions.
In spontaneous emission, the energy levels of an atom or molecule are quantized, meaning they exist in discrete energy states. As the atom or molecule spontaneously returns to a lower energy state, a photon is emitted. The probability of spontaneous emission depends on the specific energy level and the transition to a lower energy level.
This phenomenon is fundamental to various fields of physics, including quantum mechanics and optics. It plays a crucial role in explaining various natural phenomena, such as the emission of light by excited atoms in a light bulb, the decay of excited nuclei in radioactive materials, and the fluorescence of certain substances.
Spontaneous emission is distinguished from stimulated emission, where an incident photon triggers the emission of additional photons of the same frequency and direction. In contrast, spontaneous emission occurs without any external stimulus.
Etymology of SPONTANEOUS EMISSION
The word "spontaneous" originates from the Latin word "spontaneus", which means "of one's free will, willingly", or "unconstrained". It has its roots in the Latin word "sponte", meaning "of one's own accord" or "voluntarily".
The word "emission" comes from the Latin word "emissio", which means "a sending out" or "a letting go". It is derived from the Latin word "emittere", meaning "to send forth" or "to release".
In the context of physics, "spontaneous emission" refers to the natural and unforced release of electromagnetic radiation or particles by an atom or molecule. The term likely came into use in the scientific community to describe this phenomenon, combining the sense of something happening willingly or voluntarily (spontaneous) and the act of releasing or sending out (emission).
