and gamma rays are commonly used in these procedures. The most important photochemical reaction is photosynthesis. Carbon-dioxide and water combine with chlorophyll as a catalyst to give off oxygen. Photochemical reactions are caused by photons that are given off by the light source. The reactant molecules absorb the photons and get excited. They are at such an excited state, they can decompose, ionize, cause a reaction with other molecules, or give off heat. Another science that uses chemical reactions is Biochemistry. They use them to produce products that a person either can't produce or cannot do as well as they should. The best example of this the production of insulin. It was first produced in very tiny beads until someone realized that the body does in a very similar way. The person was Robert B. Merrifeild. He was the first to urge scientists to study living systems for the answers to problems that could be solved with synthesizing chemical reactions in the body. This was actually the first step toward the development of bionics. Scientists today are still toying with chemical reactions. They are trying to control them with lasers. Scientists are trying to use lasers to prod a chemical reaction that could go one way or another, the way they want it to. They want to direct the molecules in one direction. The control of photons to excite molecules and cause reactions has been elusive. Recently, though, chemist Robert J. Gordon at the University of Illinois achieved "coherent phase control of hydrogen disulfide molecules by firing ultraviolet lasers of different wavelengths at them." Laser chemistry looks promising and is a way that chemistry is still being expanded. Again, chemical reactions are the main part of a branch of chemistry. Here again, scientists are playing with chemical reactions. In April of 1995, a chemist named Peter Schultz and a physicist named Paul McEuen of the University of Cali...
