Solution to task 626 from Chertov´s for extramural stud

Solution to task 626 from Chertov´s for extramural stud

626. The average lifetime of an atom in an excited state is Δt ≈ 10-8 s. At the transition of an atom to the normal state, it is emitted by a photon, the average wavelength <λ> of which is 600 nm. Estimate the width Δλ of the emitted spectral line, if it does not broaden due to other processes.