Chapter 11, Problem 11G.5DQ

Interpretation Introduction

Interpretation:

The principle of four level laser has to be stated.

Concept introduction:

Electronic spectra are formed by the excitation and relaxation process of electrons.  The excitation process is due to the transition of an electron from a lower energy level to a higher energy level.  The relaxation process is due to the transition of an electron from a higher energy level to lower energy level.