Question

Naturally occurring hydrogen gas contains a small fraction of deuterium (hydrogen with a proton and a neutron in its nucleus).

If the spectral emmision lines due to deuterium were visible through a diffraction grating, would you be able to resolve them from the emmision lines of hydrogen? Why do you suppose the deuterium lines are not visible in a commercially prepared H2 lamp?

Answer 1

Generally, the specteral lines emission is due to the electron transition between two energy levels of the given atom

In a discharge tube, we can see that, the balmer series of omission of lines from deuterium are at slightly shorter wave lengths than those from hydrogen, because of different masses of hydrogen and deuterium Nuclei

These angular splitting of balmer lines from Hydrogen/ deuterium in the taken discharge tube were measured, and here the two angles were same within 0.01

Emperial formula by balmer