Detailed methods for measuring fluorescence quantum yields are available on-line, such as here:

http://www.horiba.com/fileadmin/uploads/Scientific/Documents/Fluorescence/quantumyieldstrad.pdf

http://iss.com/resources/research/technical_notes/PC1_MeasQuantumYldVinci.html

http://www.fluortools.com/software/ae/documentation/qy

The emissions that have calculated first after reacting the sample molecules with other materials like (OPA) with (GSH) to form complex can be detected, XRF is an atomic emission method, similar in this respect to optical emission. Such methods measure the wavelength and intensity of ‘light’ (X-rays in this case) emitted by energizedatoms in the sample. In XRF, irradiation by a primary X-ray beam from an X-ray tube, causes emission of fluorescent X-rays with discrete energies characteristic of the elements present in the sample.

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In laymen, its a ratio of photon emitted to photon absorbed. You take the absorbance spectra and emission spectra, calculate the area under the boundary of excitation and emission spectra by integrating the peak. Thereafter, take the ratio of emission value to excitation/absorbance value.

If you want absolute quantum yield, it is very hard to measure keeping laboratory conditions in mind, since fluorescence is very sensitive to its local physico-chemical environment.

Thank you,..

Short answer:

simplest is to use a reference molecule (in the same solvent) with a known QY at a concentration that the absorption of the excitation light is small

This question has been asked several times before here at ResearchGate here just a few

https://www.researchgate.net/post/How_to_measure_photoluminescence_quantum_yield

https://www.researchgate.net/post/How_can_I_calculate_the_quantum_yield_from_the_fluorescence_spectrum

https://www.researchgate.net/post/How_to_calculate_the_quantum_yield_of_fluorescent_materials

Thank you, Sir

You can calculate Quantum Yield by following this link:

https://www.instanano.com/2021/02/quantum-yield-from-photoluminescence-pl.html

Check it out:

https://www.mylabstock.com/beyond-the-glow-exploring-the-quantum-yield-of-fluorescent-molecules/