Compton wavelength

A particle's Compton wavelength is a value used in calculation of Compton scattering and some other quantum-mechanical phenomena. It is also used as a general threshold regarding the size of interactions: that if the interaction involves distances less than the Compton wavelength, then quantum mechanical considerations are necessary in its analysis.

    h
λ = ——
    mc

• λ - particle's Compton wavelength.
• h - Planck constant.
• c - speed of light.
• m - particle's mass.

Being inversely proportional to a particle's mass, it is an equivalent measure. It is a lower bound on a particle's possible de Broglie wavelength, which additionally depends upon the particle's velocity. The above formula is the same as that of the de Broglie wavelength except using the speed of light, c rather than the particle's velocity, v.

The term reduced Compton wavelength is used for the Compton wavelength divided by 2π, i.e., ℏ/mc, ℏ being the reduced Planck constant. Sometimes mention of a Compton wavelength is referring to this reduced Compton wavelength.

Of particular interest is the Compton wavelength of the electron, of relevance to electron scattering.