<Li> In 90% acetone - water, the peak absorption wavelengths of chlorophyll a are 430 nm and 664 nm; peaks for chlorophyll b are 460 nm and 647 nm; peaks for chlorophyll c1 are 442 nm and 630 nm; peaks for chlorophyll c2 are 444 nm and 630 nm; peaks for chlorophyll d are 401 nm, 455 nm and 696 nm . </Li> <P> By measuring the absorption of light in the red and far red regions, it is possible to estimate the concentration of chlorophyll within a leaf . </P> <P> Ratio fluorescence emission can be used to measure chlorophyll content . By exciting chlorophyll "a" fluorescence at a lower wavelength, the ratio of chlorophyll fluorescence emission at 705 nm + / - 10 nm and 735 nm + / - 10 nm can provide a linear relationship of chlorophyll content when compared to chemical testing . The ratio F735 / F700 provided a correlation value of r 0.96 compared to chemical testing in the range from 41 mg m up to 675 mg m . Gitelson also developed a formula for direct readout of chlorophyll content in mg m . The formula provided a reliable method of measuring chlorophyll content from 41 mg m up to 675 mg m with a correlation r value of 0.95 . </P> <P> In plants, chlorophyll may be synthesized from succinyl - CoA and glycine, although the immediate precursor to chlorophyll a and b is protochlorophyllide . In Angiosperm plants, the last step, the conversion of protochlorophyllide to chlorophyll, is light - dependent and such plants are pale (etiolated) if grown in darkness . Non-vascular plants and green algae have an additional light - independent enzyme and grow green even in darkness . </P>

What wavelength of light does chlorophyll a absorb