Pigments and dyes absorb and reflect visible light based on their molecular structure, which determines which wavelengths (colors) of light they absorb and which they reflect or transmit.
1. Absorption of Light
- Pigments and dyes have electrons that can absorb specific energies of visible light.
- When light shines on them, certain wavelengths are absorbed as electrons jump to higher energy levels.
- The wavelengths absorbed depend on the chemical bonds and arrangement of atoms in the molecule.
2. Reflection and Transmission
- The wavelengths not absorbed are either:
- Reflected (in the case of pigments, which are usually solid and opaque)
- Transmitted (in the case of dyes, which are often transparent or used in solutions)
- The combination of unabsorbed wavelengths gives the color we perceive.
3. Perceived Color
- If a pigment absorbs blue and green light, it may reflect red, and the object will appear red.
- Black objects absorb all visible wavelengths.
- White objects reflect nearly all wavelengths.
4. Pigments vs. Dyes
- Pigments are usually insoluble particles suspended in a medium.
- Dyes are soluble and bond chemically with materials like fabric.