1. What is Classical Analysis of Fluorescence Anisotropy?

Definition: Classical Analysis of Fluorescence Anisotropy occurs when each optical field (pump or probe) interacts selectively with one transition only.

Purpose: This calculation helps researchers understand molecular orientation and rotational diffusion in fluorescence spectroscopy.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( r_a \) — Classical Analysis of Fluorescence Anisotropy
• \( \gamma_a \) — Angle Between Transition Dipole Moments (in radians)

Explanation: The formula relates the fluorescence anisotropy to the angle between the absorption and emission transition dipole moments.

3. Importance of Fluorescence Anisotropy Calculation

Details: This calculation is crucial for studying molecular dynamics, protein folding, and molecular interactions in solution.

4. Using the Calculator

Tips: Enter the angle between transition dipole moments in radians. The value must be ≥ 0.

5. Frequently Asked Questions (FAQ)

Q1: What is the physical meaning of fluorescence anisotropy?
A: It measures the polarization of emitted light relative to the polarization of the excitation light, providing information about molecular rotation.

Q2: What range of values can fluorescence anisotropy take?
A: The theoretical range is from -0.2 to 0.4, with 0.4 representing complete alignment and 0 representing random orientation.

Q3: How do I convert degrees to radians for the angle input?
A: Multiply degrees by π/180 (approximately 0.0174533) to convert to radians.

Q4: What affects fluorescence anisotropy in real experiments?
A: Factors include molecular size, solvent viscosity, temperature, and the lifetime of the excited state.

Q5: When would anisotropy be zero?
A: Anisotropy is zero when the angle is the "magic angle" (approximately 54.7° or 0.955 radians) where cos²θ = 1/3.