Quantum Yield Formula:
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Definition: Quantum Yield of Fluorescence is a measure of the efficiency of photon emission defined by the ratio of the number of photons emitted to the number of photons absorbed.
Purpose: It helps researchers quantify the fluorescence efficiency of molecules and materials, which is crucial in spectroscopy, material science, and biochemical applications.
The calculator uses the formula:
Where:
Explanation: The quantum yield is calculated as the radiative rate divided by the sum of all possible deactivation pathways.
Details: Accurate quantum yield measurements are essential for characterizing fluorescent materials, designing optical devices, and understanding photophysical processes.
Tips: Enter all rate constants in Hz. The quantum yield will be between 0 (no fluorescence) and 1 (perfect fluorescence efficiency).
Q1: What is a typical quantum yield value?
A: Most fluorescent dyes have quantum yields between 0.1 and 0.9. Perfect fluorophores approach 1.0.
Q2: How is the radiative rate determined experimentally?
A: It can be measured using time-resolved fluorescence spectroscopy or calculated from absorption and emission spectra.
Q3: What factors affect quantum yield?
A: Temperature, solvent, molecular structure, and presence of quenchers all influence quantum yield.
Q4: What's the difference between internal conversion and intersystem crossing?
A: Both are non-radiative processes, but intersystem crossing involves a spin state change (singlet to triplet).
Q5: Why include the quenching constant?
A: Quenching represents additional pathways for excited state deactivation that compete with fluorescence.