text: 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.