The wavelength of light most absorbed during photosynthesis is

The wavelength of light most absorbed during photosynthesis is 660 nm.
Not all wavelengths of light can support photosynthesis. The photosynthetic action spectrum depends on the type of accessory pigments present. For example, in green plants, the action spectrum resembles the absorption spectrum for chlorophylls and carotenoids with absorption peaks in violet-blue and red light.
The non-absorbed part of the light spectrum is what gives photosynthetic organisms their colour and is the least effective for photosynthesis in the respective organisms.