Doppler broadening

In molecules shifts the apparent frequency of each emitter. The many different velocities of the emitting gas result in many small shifts, the cumulative effect of which is to broaden the line. The resulting line profile is known as a Doppler profile. The broadening is dependent only on the wavelength of the line, the mass of the emitting particle and the temperature, and can therefore be a very useful method for measuring the temperature of an emitting gas.