A WAVE-OPTICS EFFECT WHICH ENHANCES LIGHT ABSORPTION BY CHLOROPHYLL IN VIVO

Abstract Light is widely thought to move through cells and tissues as rays. Actually light is inherently wave-like; ray motion is a special simple case of wave motion. To determine how well rays simulate light propagation and gradients within cells, absorption and scattering by particles were calculated with two sets of equations: one based on wave propagation within the particle and the other based on ray propagation. The ray model is found to substantially describe absorption at all particle size levels; however, it does not correctly describe scattering. Furthermore, for biological cells and structures larger than λ, the wave equations predict absorption cross sections which are 8–10% larger than expected on the basis of ray optics and extraction data: i.e. absorption is increased by a peculiar wave optics effect. This effect must enhance the efficiency with which the plants collect light energy for photosynthesis. The effect should be accounted for in corrections for the sieve effect.