Well, you are going to need to use the physics equation E=h*C/ λ to convert the light wavelength to energy per photon, first convert nano-meters into meters then plug this into the equation modified for wavelength.

E= Energy in (joules per photon)
C = Speed of Light in (meters per second)
h = Plank’s constant
λ = wavelength in meters

Next, Remember that photons hit one atom or Atoms per photon a physics concept called the photoelectric effect. so, take the Energy per photon times how many moles you have or ΣE = E * (Atoms) , Always remember to convert your micro-moles into Atoms.

E = Energy per Photon (Joules per photon)
Atoms = How many atoms are being hit by photons in (Atoms * Photons)
ΣE = Sum of Energy of all photons hitting your atoms in (Joules)

Lastly, you can convert the joules into another unit of energy being kilowatt hours