action spectra

[Husain Qutbuddin]

I would like to know whether anyone anywhere has  done an experiment to
find out which spectrums of light provide the main energy  for
photosynthesis. By, maybe, exposing the plant to different spectrums and
seeing in which they photosynthesize most. I would also like to know the
most  effective way of measuring photosynthesis. Would measuring how much
the plant  grows during a time be an indication of how much it is
photosynthesizing?   I would be grateful if you could answer this, or  even
give me a couple of links to which I can refer to.   Thankyou very much,
sincerely, Husain.