Question

Why only uv and visible light are responsible for electron excitation?

Answer 1

When we speak of a molecule as being raised to a higher electronic level we mean that an electron has been changed from one orbital to another orbital of higher energy. This electron can be of any kinds we have encountered –a σelectron, a π electron or an n electron. In Ultraviolet region we are confined only to the excitation of the comparatively loosely held n and πelectrons.