Question

Under what conditions can a Stokes shift (see Section 6C-6) occur in atomic spectroscopy?

Short answer

Stokes shift occurs due to the condition of excited electrons which reached to the high energy state and fell back.

Step-by-step solution

Given Information

Explain the conditions can a Stokes shift occur in atomic spectroscopy.

Explanation

In atomic absorption spectroscopy; when light passes through an atom or molecule, the light is absorbed by the molecule or atom only when the wavelength of light is equal to the energy difference of the two energy levels of an atom. These two energy levels of an atom are absorption and emission. This process of Stokes shift can be elaborated by the following graph:

This graph is given by intensity vs. wavelength or frequency. Here, we can see that the difference of absorption and emission spectra determines stokes shift. This process occurs in same electron transition.

In atomic spectroscopy; Stokes shift occurs due to the condition of excited electron. The excited electron reaches a higher energy state. After reaching a high energy state, it emits photon and bounced back to the lower energy state.

Conclusion

After studying the definition of Stokes shift which says that this shift is the difference in the energy levels of atom and molecule. By this we can conclude that the in atomic spectroscopy, condition for the Stokes shift in excited electron which reached to the high energy state and emits photon. After that, it bounced back to the lower energy state.