In
atomic physics,
Doppler broadening is the broadening of
spectral lines due to the
Doppler effect caused by a distribution of velocities of
atoms or
molecules. Different velocities of the
emitting particles result in different Doppler shifts, the cumulative effect of which is the line broadening. This resulting line profile is known as a
Doppler profile. A particular case is the
thermal Doppler broadening due to the
thermal motion of the particles. Then, the broadening depends only on the
frequency of the spectral line, the
mass of the emitting particles, and their
temperature, and therefore can be used for inferring the temperature of an emitting body.