Quantum Yield of Fluorescence Formula:
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Definition: Quantum Yield of Fluorescence is a measure of the efficiency of photon emission as 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, microscopy, and material science.
The calculator uses the formula:
Where:
Explanation: The formula represents the fraction of excited molecules that decay through fluorescence relative to all possible decay pathways.
Details: Quantum yield is crucial for comparing fluorophores, designing fluorescent probes, and understanding photophysical processes in materials.
Tips: Enter all rate constants in Hz. The quantum yield will be between 0 (no fluorescence) and 1 (100% efficient fluorescence).
Q1: What does a quantum yield of 0.5 mean?
A: It means 50% of the excited molecules decay through fluorescence, while the other 50% decay through non-radiative pathways.
Q2: What's a typical value for Kf?
A: Typical fluorescence rate constants range from 106 to 109 Hz, depending on the fluorophore.
Q3: How do I measure these rate constants experimentally?
A: Kf can be determined from the natural lifetime, while RIC and KISC are often derived from quantum yield and lifetime measurements.
Q4: Can quantum yield be greater than 1?
A: Normally no, but in cases of photon upconversion or multiple exciton generation, apparent yields >1 can occur.
Q5: What affects quantum yield in real systems?
A: Temperature, solvent, molecular structure, and competing photochemical processes can all influence quantum yield.