Narrow-band collisional activation technique for ion trap mass spectrometers

Narrow-bandwidth signals were applied to the end caps of an ion trap mass s pectrometer to excite ions during collisional activation. Excitation wavefo rms were created from a single-frequency component and a random noise compo nent using a multiplier circuit. Tandem and higher order mass spectrometry experiments (MS3) can be performed without optimization of the supplemental frequency applied to the end cap electrodes. The usefulness of this method of ion excitation is demonstrated using singly and multiply protonated pep tide ions as well as sodium-cationized carbohydrates.