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Chemistry LibreTexts

Multi-Colored Luminescence of Lucigenin

Chemical Concept Demonstrated

  • Chemiluminescence across the entire visible spectrum

Demonstration

Solution A

  • Dissolved NaOH in distilled water.
  • Added ethanol and 30% H2O2.

Solution B

  • Dissolved lucigenin in distilled water.

Solution C

  • Dissolved rhodamine in ethanol.

Solution D

  • Dissolved fluorescein in ethanol.
  • Using the glass spiral assembly, solutions A and B are poured into the funnels.luminol.gif
  • Next, 5 mL of solution C are added. Then, 5 mL of solution D. Repeat.

Observations

The luminescence will begin blue, then shifts to red upon addition of the third solution.  When the fourth solution is added, the reaction shifts to the green end of the spectrum.  The third and fourth solutions are alternated, and the entire spiral emits various glows throughout the visible spectrum.

Explanation

Different reactions release energy in different ways.  Just as different amounts of heat are emitted during the course of different exothermic reactions, different wavelengths of light are emitted during the course of different chemiluminescent reactions.  This demonstration involves three different reactions that produce three different wavelengths of light.  The mixtures of these reactions produce various colors of light throughout the entire length of the spiral.

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