在原子物理学中，都卜勒增宽（Doppler broadening）是因为原子或分子的运动速度分布产生的多普勒效应造成谱线增宽的现象。自发发射分子的不同运动速度造成了不同的都卜勒位移，而这些效应的线性累积结果就是谱线增宽。因为以上效应产生的线型轮廓即为都卜勒轮廓（Doppler profile）。一个特别的，也可能最重要的状况是因为粒子热运动而发生的热都卜勒增宽。接着，谱线增宽程度只取决于谱线的频率、谱线发射分子的质量、温度；因此都卜勒增宽可用以推测辐射体的温度。

饱和吸收光谱学（或称为无都卜勒光谱学，Doppler-free spectroscopy）可用来发现原子跃迁的真实频率而不需要将样品降温至都卜勒增宽效应最低的温度值。

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.