Radioactive Tracers Applications of Nonionizing Radiation

A tiny amount of a radioisotope mixed with a large amount of the stable isotope can act as a tracer, a chemical beacon emitting nonionizing radiation that signals the presence of the substance. 

Far more complex reaction pathways can he followed with tracers as well. The photosynthetic pathway, the most essential and widespread metaholic process on Earth, in which energy from sunlight is used to form the chemical bonds of glucose, has an overall reaction that looks quite simple  

However, the actual process is extremely complex 13 enzyme-catalyzed steps are required to incorporate each molecule of CO2, so the six CO2 molecules incorporated to form one molecule of C6H12O6 require six repetitions of the pathway. Melvin Calvin and his coworkers took seven years to determine the pathway, using in CO2 as the tracer and painstakingly separating the products formed after different times of light exposure. Calvin won the Nobel Prize in chemistry in 1961 for this remarkable achievement. 

When RCO OH reacts with the unlabeled alcohol, the water contains Thus, the alcohol supplies the —OR part of the ester, and the acid supplies the RC=0 part. 

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