As we used "slow motion" in a football match on TV to reveal the movements of the players and the ball when a goal is scored, chemical reactions are the same, chemists need to follow chemical reactions. Where Dr.Ahmed H. Zewail, has studied atoms and molecules in "slow motion" during a reaction and seen what actually happens when chemical bonds break and new ones are created.
Dr.Zewail's technique can be described as the world's fastest camera. He uses laser flashes of such short duration that we are down to the time scale on which the reactions actually happen - femtoseconds (fs). One femtosecond is 1/15 seconds, that is, 0.000000000000001 seconds. This area of physical chemistry has been named femtochemistry.
Femtochemistry enables us to understand why certain chemical reactions take place but not others. We can also explain why the speed and yield of reactions depend on temperature. Scientists all over the world are studying processes with femtosecond spectroscope in gases, in fluids and in solids, on surfaces and in polymers. Applications range from how catalysts function and how molecular electronic components must be designed, to the most delicate mechanisms in life processes and how the medicines of the future should be produced.