Chapter 7.3 - Solar Energy

• Most of the radiation reaching the earth is within the Visible-Light Range

• Our retinal pigments can only ¨see¨ (absorb) wavelengths between 700 nm and 400 nm of light, a spectrum called visible light.

PIgments/Photosystems

• Pigment molecules absorb wavelengths of light

• Wavelengths that are not absorbed by pigments are REFLECTED/TRANSMITTED (the color we see)

Absorption Spectrum - a graph showing th relative absorption of the various colors of the rainbow

• Chlorophyll is green because it absorbs much of the reds and blues of white light and reflects green light

• Plants contain chlorophyll A + B - both absorb violet, blue, and red light better

• Photosystem - consist of a pigment complex, molecules of chlorophyll a + b

• Carotenoids - electron recceptor molecules within the thylakoid membrane