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The Doppler effect (also Doppler shift) is the change in the frequency of a wave in relation to an observer who is moving relative to the source of the wave. [ 1 ] [ 2 ] [ 3 ] The Doppler effect is named after the physicist Christian Doppler , who described the phenomenon in 1842.
An example of a Doppler broadened line profile. The solid line represents an un-broadened emission profile, and the dashed line represents a broadened emission profile. In atomic physics, Doppler broadening is broadening of spectral lines due to the Doppler effect caused by a distribution of velocities of atoms or molecules.
To overcome the problem of Doppler broadening without cooling down the sample to millikelvin temperatures, a classical pump–probe scheme is used. A laser with a relatively high intensity is sent through the atomic vapor, known as the pump beam.
The relativistic Doppler effect is the change in frequency, wavelength and amplitude [1] of light, caused by the relative motion of the source and the observer (as in the classical Doppler effect, first proposed by Christian Doppler in 1842 [2]), when taking into account effects described by the special theory of relativity.
Relativistic Doppler effect (Doppler effects) (special relativity) Renner–Teller effect (molecular physics) Reverse Cerenkov effect (physics) Reverse short-channel effect (transistors) Ringelmann effect (social psychology) Ripple effect (education) (sociology) Robin Hood effect (income distribution) (Robin Hood) (socioeconomics) (taxation)
The Doppler temperature is the minimum temperature achievable with Doppler cooling. When a photon is absorbed by an atom counter-propagating to the light source, its velocity is decreased by momentum conservation. When the absorbed photon is spontaneously emitted by the excited atom, the atom receives a momentum kick in a random direction.
Doppler effect, in general, happens for the wave at all speed (including the speed that near the speed of light). Classical treatment for Doppler Effect may take sound wave for example. Using sound wave for example, the classical treatment is only valid if the observer and source are both slower than the speed of sound relative to the medium.
In the Mössbauer effect, a narrow resonance for nuclear gamma emission and absorption results from the momentum of recoil being delivered to a surrounding crystal lattice rather than to the emitting or absorbing nucleus alone. When this occurs, no gamma energy is lost to the kinetic energy of recoiling nuclei at either the emitting or ...