Why did Manfred Eigen receive the 1967 Nobel Prize?

Manfred Eigen was awarded the 1967 Nobel Prize for Chemistry for his pioneering work on extremely rapid chemical reactions.1

He achieved this by introducing relaxation techniques, which allow scientists to study reactions that occur too quickly for traditional mixing methods. In these techniques, a system already at equilibrium is subjected to a rapid external disturbance—such as a sudden change in temperature, known as the temperature-jump method—which briefly disrupts the equilibrium.12

By using spectroscopy to observe how the system "relaxes" back to a new equilibrium state, Eigen was able to measure the kinetics of processes that were previously inaccessible. This breakthrough enabled the study of fundamental chemical phenomena, including the rate of hydrogen ion formation and the kinetics of complex molecular rearrangements.12