Question

What determines natural line widths for atomic emission and absorption lines? About how broad are these widths, typically?

Short answer

Spectral lines are lines which help in identifying the atoms and molecules. These are a result of absorption or emission of light in a comparatively narrower frequency range compared to the frequencies nearby.

Step-by-step solution

Given Information

Give the factor determining the line widths for absorption lines and atomic emission also the widths of these lines.

Factor determining the line widths for absorption lines and atomic emission 

Natural line widths are those line widths in which broadening takes place only due to uncertainty principle.

Generally, Heisenberg’s uncertainty principle and a lifetime of excited state are used in determining the natural line widths.

For atoms, the radiative lifetimes are generally in the order of 10^-8 seconds. The natural line widths which are broad are therefore in the order of 10^-5 nanometers.