Ambient temperature K 0 500K 300K 300K 300K (room temperature) 77K 77K (liquid nitrogen) 4.2K 4.2K (liquid helium) 0K 0 (absolute zero) white 0.7 green 1.0 #ffccff 1.0 #999999 1.0 #ff99ff 1.0 red 1.0 blue 1.0 yellow 1.0 #cccccc 1.0 #ccffcc 1.0 #cccc00 1.5 #cccc00 1.5 GaAs 1.422eV #ccccff 4.070eV 12.847 0.462e18/cm3 0.942e19/cm3 Al(0.3)Ga(0.7)As #9999ff 1.797eV 3.827eV 11.9 0.857e18/cm3 0.111e20/cm3 Au #ffff66