https://doi.org/10.1351/goldbook.08663
Increase in the line width of a spectral line of a gas due to molecular collisions and other intermolecular interactions that reduce the lifetime of an excited state.
Note:
At pressures sufficiently low that the line width is far smaller than the line wavelength, the line width increases linearly with pressure, the broadening is homogeneous and the line shape is Lorentzian.
At pressures sufficiently low that the line width is far smaller than the line wavelength, the line width increases linearly with pressure, the broadening is homogeneous and the line shape is Lorentzian.