Quantum Yield of Fluorescence Calculator

Quantum Yield of Fluorescence Formula:

\[ φ_{fl} = \frac{K_f}{K_f + R_{IC} + K_{ISC}} \]

Rate Constant of Fluoroscence (K_f):

Rate of Internal Conversion (R_IC):

Rate Constant of Intersystem Crossing (K_ISC):

Quantum Yield of Fluorescence (φ_fl):

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1. What is Quantum Yield of Fluorescence?

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.

2. How Does the Calculator Work?

The calculator uses the formula:

\[ φ_{fl} = \frac{K_f}{K_f + R_{IC} + K_{ISC}} \]

Where:

\( φ_{fl} \) — Quantum Yield of Fluorescence (unitless, between 0 and 1)
\( K_f \) — Rate Constant of Fluoroscence (Hz)
\( R_{IC} \) — Rate of Internal Conversion (Hz)
\( K_{ISC} \) — Rate Constant of Intersystem Crossing (Hz)

Explanation: The formula represents the fraction of excited molecules that decay through fluorescence relative to all possible decay pathways.

3. Importance of Quantum Yield Calculation

Details: Quantum yield is crucial for comparing fluorophores, designing fluorescent probes, and understanding photophysical processes in materials.

4. Using the Calculator

Tips: Enter all rate constants in Hz. The quantum yield will be between 0 (no fluorescence) and 1 (100% efficient fluorescence).

5. Frequently Asked Questions (FAQ)

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 K_f?
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: K_f can be determined from the natural lifetime, while R_IC and K_ISC 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.