1. What is ISC Rate Constant?

Definition: The ISC (Intersystem Crossing) Rate Constant (K_i) quantifies the rate of transition from an excited singlet state to a triplet state.

Purpose: It helps in understanding and predicting photophysical processes in molecular systems, particularly in photochemistry and materials science.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( K_i \) — Rate Constant of ISC (Hz)
• \( R_{ISC} \) — Rate of Intersystem Crossing (mol/(m³·s))
• \( [M_{S1}] \) — Singlet State Concentration (mol/m³)

Explanation: The rate constant is calculated by multiplying the rate of intersystem crossing by the concentration of molecules in the singlet excited state.

3. Importance of ISC Rate Constant

Details: Understanding ISC rates is crucial for designing materials for applications like organic light-emitting diodes (OLEDs), photodynamic therapy, and molecular sensors.

4. Using the Calculator

Tips: Enter the rate of intersystem crossing in mol/(m³·s) and singlet state concentration in mol/m³. All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What is intersystem crossing?
A: It's an isoenergetic radiationless process involving a transition between two electronic states with different spin multiplicity.

Q2: What are typical values for R_ISC?
A: Values vary widely but typically range from 10³ to 10⁹ mol/(m³·s) depending on the molecular system.

Q3: How is singlet state concentration determined?
A: It can be measured experimentally using spectroscopic techniques or calculated theoretically.

Q4: What factors affect the ISC rate constant?
A: Spin-orbit coupling, energy gap between states, molecular structure, and environmental factors.

Q5: Why is K_i important in OLED design?
A: It helps predict the efficiency of triplet formation, which is crucial for phosphorescent OLED materials.