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The photon also carries spin angular momentum, which is related to photon polarization. (Beams of light also exhibit properties described as orbital angular momentum of light). The angular momentum of the photon has two possible values, either +ħ or −ħ. These two possible values correspond to the two possible pure states of circular ...
The photons of a light beam have a characteristic energy, called photon energy, which is proportional to the frequency of the light.In the photoemission process, when an electron within some material absorbs the energy of a photon and acquires more energy than its binding energy, it is likely to be ejected.
As a photon is absorbed by an atom, it excites the atom, elevating an electron to a higher energy level (one that is on average farther from the nucleus). When an electron in an excited molecule or atom descends to a lower energy level, it emits a photon of light at a frequency corresponding to the energy difference.
The photon having non-zero linear momentum, one could imagine that it has a non-vanishing rest mass m 0, which is its mass at zero speed. However, we will now show that this is not the case: m 0 = 0. Since the photon propagates with the speed of light, special relativity is called for. The relativistic expressions for energy and momentum ...
If a photon of light hits the atom it will be absorbed if, and only if, energy of that photon is equal to the difference between the ground state and another energy level in that atom. This raises the electron to a higher energy level.
Fig. 3: Energies of a photon at 500 keV and an electron after Compton scattering. A photon γ with wavelength λ collides with an electron e in an atom, which is treated as being at rest. The collision causes the electron to recoil, and a new photon γ ′ with wavelength λ ′ emerges at angle θ from the photon's
If a light source ('the atom') is in an excited state with energy , it may spontaneously decay to a lower lying level (e.g., the ground state) with energy , releasing the difference in energy between the two states as a photon.
Electron excitation is the transfer of a bound electron to a more energetic, but still bound state. This can be done by photoexcitation (PE), where the electron absorbs a photon and gains all its energy [1] or by collisional excitation (CE), where the electron receives energy from a collision with another, energetic electron. [2]