Principles of collisional activation in analytical mass spectrometry

Collisional activation has played an essential role in the development of mass spectrometry/mass spectrometry (MS/MS). It was the first activation method to be employed and continues to be by far the most widely used. As instrumentation for MS/MS has evolved it has been found that collisional activation can be effected under a remarkably wide range of conditions for a wide range of ions. It is fair to conclude from the growth of MS/MS over the past fifteen years that collisional activation has been spectacularly successful. However, it has limitations. As a community, we have learned much over the years regarding these limitations both from empirical and fundamental points of view. This overview provides background on the development of collisional activation and discusses the importance of the interaction potential and timing on mechanisms for energy transfer. Parts of the discussion is devoted to changing reference frames from the laboratory to the center of mass to simplify visualizing what is possible and what is probable in collisional activation.