If laser beams of a predetermined wavelength are irradiated, {HEAD ~ electrons} are excited beyond {TAIL ~ the forbidden band} by optical energy in the semiconductor electrode of the hydrogen producing unit 
are excited beyond
If laser beams of a predetermined wavelength are irradiated , { HEAD ~ electrons } are excited beyond { TAIL ~ the forbidden band } by optical energy in the semiconductor electrode of the hydrogen producing unit
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH