Question

Why the transition from the excited state to ground state occurs in the absorption spectra?

Answer 1

Light Absorption – Formation of the Excited State

Photochemistry is based on the reaction/reactivity of molecules in their excited state after they have absorbed light. By “light”, we mean that part of the electromagnetic spectrum that can promote electrons in the outer atomic orbitals to unoccupied orbitals – i.e. electrons near or at the highest occupied molecular orbital (HOMO) to orbitals near or including the lowest unoccupied molecular orbital (LUMO). To do this, the light must be of sufficient energy to promote electrons between electronic energy levels, and this is found to be light in