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Photonic molecules are a form of matter in which photons bind together to form "molecules". [1] [2] [3] They were first predicted in 2007.Photonic molecules are formed when individual (massless) photons "interact with each other so strongly that they act as though they have mass". [4]
To create an electron-positron pair, the total energy of the photons, in the rest frame, must be at least 2m e c 2 = 2 × 0.511 MeV = 1.022 MeV (m e is the mass of one electron and c is the speed of light in vacuum), an energy value that corresponds to soft gamma ray photons.
Because photons have zero rest mass, no wave function defined for a photon can have all the properties familiar from wave functions in non-relativistic quantum mechanics. [ f ] In order to avoid these difficulties, physicists employ the second-quantized theory of photons described below, quantum electrodynamics , in which photons are quantized ...
This fermion pair can be leptons or quarks. Thus, two-photon physics experiments can be used as ways to study the photon structure, or, somewhat metaphorically, what is "inside" the photon. The photon fluctuates into a fermion–antifermion pair. Creation of a fermion–antifermion pair through the direct two-photon interaction.
The SI unit of molar absorption coefficient is the square metre per mole (m 2 /mol), but in practice, quantities are usually expressed in terms of M −1 ⋅cm −1 or L⋅mol −1 ⋅cm −1 (the latter two units are both equal to 0.1 m 2 /mol).
By recording the attenuation of light for various wavelengths, an absorption spectrum can be obtained. In physics, absorption of electromagnetic radiation is how matter (typically electrons bound in atoms) takes up a photon's energy—and so transforms electromagnetic energy into internal energy of the absorber (for example, thermal energy). [1]
Here, a proton, consisting of two up quarks and a down, decays into a pion, consisting of an up and anti-up, and a positron, via an X boson with electric charge − 4 / 3 e. In particle physics, proton decay is a hypothetical form of particle decay in which the proton decays into lighter subatomic particles, such as a neutral pion and a ...
It is based on the idea that emission and absorption of a photon corresponds to the creation and annihilation of a particle–antiparticle pair. The neutrino theory of light is not currently accepted as part of mainstream physics, as according to the Standard Model the photon is an elementary particle , a gauge boson .