Search results
Results from the WOW.Com Content Network
The typical observed radiant emittance of biological tissues in the visible and ultraviolet frequencies ranges from 10 −17 to 10 −23 W/cm 2 with a photon count from a few to nearly 1000 photons per cm 2 in the range of 200 nm to 800 nm. [1]
Photobiology is the scientific study of the beneficial and harmful interactions of light (technically, non-ionizing radiation) in living organisms. [1] The field includes the study of photophysics, photochemistry, photosynthesis, photomorphogenesis, visual processing, circadian rhythms, photomovement, bioluminescence, and ultraviolet radiation effects.
24% of the absorbed photon energy is lost due to degrading short wavelength photons to the 700 nm energy level; 68% of the used energy is lost in conversion into d-glucose; 35–45% of the glucose is consumed by the leaf in the processes of dark and photo respiration; Stated another way: 100% sunlight → non-bioavailable photons waste is 47% ...
Weighting factor for photosynthesis. The photon-weighted curve is for converting PPF to YPF; the energy-weighted curve is for weighting PAR expressed in watts or joules. There are two common measures of photosynthetically active radiation: photosynthetic photon flux (PPF) and yield photon flux (YPF).
Humans can make or change abiotic factors in a species' environment. For instance, fertilizers can affect a snail's habitat, or the greenhouse gases which humans utilize can change marine pH levels. Abiotic components include physical conditions and non-living resources that affect living organisms in terms of growth, maintenance, and ...
The factor = where is the quantum efficiency describes the efficiency of the photon counter. A perfect detector would have η = 1 {\displaystyle \eta =1} . I {\displaystyle I} is the intensity incident on an area A of the photodetector and is given by [ 4 ]
A corollary of Kasha's rule is the Vavilov rule, which states that the quantum yield of luminescence is generally independent of the excitation wavelength. [4] [7] This can be understood as a consequence of the tendency – implied by Kasha's rule – for molecules in upper states to relax to the lowest excited state non-radiatively.
This cross section depends on the energy of the photon (proportional to its wavenumber) and the species being considered i.e. it depends on the structure of the molecular species. In the case of molecules, the photoionization cross-section can be estimated by examination of Franck-Condon factors between a ground-state molecule and the target ion.