Final answer:
The Stark-Lo Surdo effect refers to the splitting or shifting of spectral lines in a laser's active medium due to an external electric field, affecting electron energy levels and potentially enhancing laser action.
Step-by-step explanation:
The Stark-Lo Surdo effect relates to the splitting or shifting of spectral lines of atoms and molecules due to the presence of an external static electric field. This is a phenomenon that is observable in the interaction of the electromagnetic field with the active medium in a laser. In a laser, an external electric field can influence the energy levels of the electrons in the active medium, which can lead to a change in the wavelengths of the emitted light. This is particularly significant in gas lasers, where the external electric field can cause a redistribution of the population of electrons in different energy states, potentially enhancing the laser action through a process called ‘optical pumping’. The effect is named after Johannes Stark and Antonino Lo Surdo who independently discovered the phenomenon of spectral line splitting in electric fields in the early 20th century.