When the absorption maximum of a molecule changes due to internal or external factors, it's termed a spectral shift.
There are various types of spectral shifts:
Bathochromic shift (Red shift):
A shift of the absorption band towards longer wavelengths (lower energy).
It could be due to the addition of an auxochrome, a change in solvent polarity, or any factor that decreases the energy gap between the ground and excited states.
Hypochromic shift (Blue shift):
A shift of the absorption band towards shorter wavelengths (higher energy).
It could result from the removal of an auxochrome, a change in solvent polarity, or any factor that increases the energy gap between the ground and excited states.
Hyperchromic effect:
An increase in the intensity of absorption.
Hypochromic effect:
A decrease in the intensity of absorption.
