The quantum yield of the radiation induced process is known as the amount or number of times that a specific event happens per photon that is absorbed by the system. The event that happens is in terms of a chemical reaction.
The quantum yield given in the decomposition reaction for the decomposition of the reactant molecule is given in terms of molecules decomposed per photons absorbed. The quantum yield can also be defined for the chemical reactions like fluorescence.
In fluorophore, the quantum yield is also known as the emission efficiency of the given fluorophore and is given in terms of emitted photons per photons absorbed. The relative fluorescence quantum yield can also be calculated through the measurement of fluorescence of the fluorophore of a known quantum yield through the experimental parameters which are same as the substance.
REASONS FOR THE LOW QUANTUM YIELD
There are various reasons which can hamper the quantum yield of a reaction. Some of them are-
- The primary foremost photochemical reaction gets backtracked for any known or unknown reason.
- The broken down molecules might get combined to each other again which would result in the formation of the same original molecule that was present before the reaction started.
- The loss of energy of the activated molecule before it could react any further.
- The loss of energy which happens to owe to the collision between the excited molecule and the not excited molecule.
- The intensity of the light energy is also a reason that can affect the quantum yield.
EXAMPLES OF QUANTUM YIELD
- In a chemical photodegradation process, the absorption of light quantum causes the molecule to dissociate. The quantum yield becomes the number of molecules that were destroyed divided by the number of absorbed photons by the system. The quantum yield tends to be less than 1 owing to the fact that not all the photons get absorbed productively.
- The quantum yield which is greater than 1 is possible for the chain reactions which are either photoinduced or radiation induced and in which a long chain of transformations is caused by a single photon only. One such example of a reaction is the hydrogen-chlorine reaction.
- In the field of optical spectroscopy, the probability of the given quantum state formation from the system which was primarily prepared in another quantum state is known as the quantum yield.