At the first stage of photosynthesis, the light from the sun is absorbed in the light absorbing complex called the photosystem II in the thylakoid membrane. A molecule in the photosystem called chlorophyll P680 because of its absorption wavelength at 680 nm absorbs the light to commence photosynthesis.
Helium does not react with any other substances, thus the substance’s internal structure is never greatly affected and thus helium cannot have any chemical properties.