Many experiments that suggest the possible sequence of steps in a reaction mechanism have been designed, including:
* measurement of the effect of temperature (Arrhenius equation) to determine the activation energy
* spectroscopic observation of reaction intermediates
* determination of the stereochemistry of products, for example in nucleophilic substitution reactions
* measurement of the effect of isotopic substitution on the reaction rate
* for reactions in solution, measurement of the effect of pressure on the reaction rate to determine the volume change on formation of the activated complex
* for reactions of ions in solution, measurement of the effect of ionic strength on the reaction rate
* direct observation of the activated complex by pump-probe spectroscopy
* infrared chemiluminescence to detect vibrational excitation in the products
* electrospray ionization mass spectrometry.
* crossover experiments.