chlorophyll edge in astrobiology
"Earth's deciduous plants have a sharp order-of-magnitude increase in leaf reflectance between approximately 700 and 750 nm wavelength. This strong reflectance of Earth's vegetation suggests that surface biosignatures with sharp spectral features might be detectable in the spectrum of scattered light from a spatially unresolved extrasolar terrestrial planet. We assess the potential of Earth's step-function-like spectroscopic feature, referred to as the ''red edge,'' as a tool for astrobiology."
http://www.agu.org/meetings/fm05/fm05-sessions/fm05_SA52A.html