ABSTRACT
This chapter aims to develop the foundations of photochemistry in the context of analysts' need to understand and predict how chemicals, dissolved in natural waters, will behave in sunlight. It describes equipment and procedures for accurate measurement of rates of photolyis and quantum yields in the laboratory. Environmental chemists have now begun to examine in some detail environmental photochemical processes where sunlight is the energy source, reactant concentrations are low, and aerated water is the solvent. For photochemical processes the chemist must devise ways of using photolysis rates measured using artificial light sources and thin optical cells to make accurate predictions of photolysis rates in sunlight in shallow or deep and clear or turbid natural waters and at different times of year. Apparatus used to measure photochemical kinetics in the laboratory is usually either a merry-go-round reactor or optical bench. Monochromatic or narrow wavelength light is essential for accurate measurements of photochemical quantum yields.
