MULTIPLE EXCITATION COLLISIONAL ACTIVATION IN FOURIER-TRANSFORM MASS-SPECTROMETRY

Multiple excitation collisional activation (MECA) has been examined us ing Fourier-transform mass spectrometry. In analogy to recently report ed multiple excitation detection schemes, MECA is a process in which i ons are translationally excited to larger orbits by applying an RF sig nal over the desired mass range. Next, collisional cooling of the ions collapses them, spatially, back to the center of the cell, where the process can be repeated. Two examples of the utility of MECA are given . The first involves a novel way of growing cluster ions by sequential ion/molecule reactions followed by MECA. The second uses MECA to incr ease the energy deposition in a stable and difficult-to-fragment ion, thereby inducing fragmentation.