Action spectrum

An action spectrum is a graph of the rate of biological effectiveness plotted against wavelength of light.

Therefore, the action spectrum graph would show spikes above the wavelengths representing the colours red and blue.

The first action spectrum was made by T. W. Engelmann, who split light into its components by the prism and then illuminated Cladophora placed in a suspension of aerobic bacteria.

[3] As a result, action spectra have been used to measure the efficiency of different light wavelengths in disinfecting water, the rate and mechanism of photodegradation of folic acid in the blood, and the chirality of molecules to determine secondary structure.

[4][5][6] Further examples include suppression of melatonin by wavelength[7] and a variety of hazard functions, related to tissue damage from visible and near-visible light.

Absorbance spectra of free chlorophyll a ( blue ) and b ( red ) in a solvent. The action spectra of chlorophyll molecules are slightly modified in vivo depending on specific pigment-protein interactions.