Question

Why does fluorescence quenching occur?

Answer 1

Fluorescence quenching is an important process of determining or measuring the binding affinity between the ligands and proteins.

Fluorescence quenching can also be defined as reducing or decrease in the quantum yield of fluorescence from a fluorophore. This is induced by various molecular interactions aided with a quencher molecule.

This gives good overview.

Answer 2

Why does fluorescence quenching occur?

fluorescence quenching is refers to any process reduces the  fluorescence intensity of given substance

this may occur due to various factors like PH,concentration ,temperature,viscosity ,presence of oxygen,heavy metal or specific chemical substances etc

Fluorescence quenching refer to any that decreases the Fluorescence intensity of sample .a varity of molecular interaction can be  result in quenching .these include excited state ,molecular and colli=sional quenching

example of quenching agents  ,                typical fluorescence

                    Thiocyanate                 ,          Anthracene

                       cholride                    ;            Quinine

                         Nitric oxide            ;                    Naphthalene