[rekhasharma]

what is Fluoroscence quenching effect and why it occurs??

[Mitch]

Quenching refers to any process which decreases the fluorescence intensity of a given substance. A variety of processes can result in quenching, such as excited state reactions, energy transfer, complex-formation and collisional quenching. As a consequence, quenching is often heavily dependent on pressure and temperature. Molecular oxygen and the iodide ion are common chemical quenchers. Quenching poses a problem for non-instant spectroscopic methods, such as laser-induced fluorescence.