1. What Is Extinction Coefficient?

The extinction coefficient (ε) is a measure of how strongly a chemical species absorbs light at a particular wavelength. It's a fundamental parameter in spectroscopy that quantifies the absorption characteristics of a substance.

2. How Does The Calculator Work?

The calculator uses the Beer-Lambert law equation:

Where:

• \( \varepsilon \) — Extinction coefficient (M⁻¹·cm⁻¹)
• \( A \) — Absorbance (dimensionless)
• \( c \) — Concentration (molarity, M)
• \( l \) — Path length (cm)

Explanation: The equation relates the absorption of light to the properties of the material through which the light is traveling.

3. Importance Of Extinction Coefficient

Details: The extinction coefficient is crucial for quantifying concentrations of substances in solution, determining purity of samples, and studying molecular interactions in various fields including chemistry, biochemistry, and environmental science.

4. Using The Calculator

Tips: Enter absorbance (typically measured by a spectrophotometer), concentration in molar units (M), and path length in centimeters (cm). All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What are typical values for extinction coefficients?
A: Extinction coefficients vary widely depending on the substance and wavelength. They can range from near zero for non-absorbing compounds to over 100,000 M⁻¹·cm⁻¹ for strongly absorbing dyes.

Q2: How does wavelength affect extinction coefficient?
A: Extinction coefficient is wavelength-dependent. Each substance has characteristic absorption peaks where its extinction coefficient is highest.

Q3: What's the difference between extinction coefficient and absorption coefficient?
A: Extinction coefficient typically refers to molar absorptivity (M⁻¹·cm⁻¹), while absorption coefficient often refers to the decadic absorption coefficient with units of cm⁻¹.

Q4: Can extinction coefficient be used for quantitative analysis?
A: Yes, once the extinction coefficient is known for a particular substance at a specific wavelength, it can be used to determine unknown concentrations of that substance.

Q5: How is extinction coefficient determined experimentally?
A: By measuring absorbance at known concentrations and path lengths, then calculating ε = A/(c×l). Typically, multiple measurements are made to ensure accuracy.