Quantum Yield a as Function of the Wavelength

Since the light of different wavelengths can have a varying effect on the ab-sorbmg molecule, the quantum yield and thus the photochemical reaction rate usually change with wavelength. 

When the wavelengths used lie within a certain spectrum of the same nature, the quantum yield is either independent of or slightly dependent on the wavelength. An example is the decomposition of hydrogen iodide 2 HI H2 + I2, 

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