Instrument Overview
The heart of the apparatus is a pair of coupled electrostatic ion traps, one for cations, the other for anions or electrons. When trapped, the ions oscillate back and forth and the frequency of this oscillation, recorded by a pick-up electrode, may be Fourier-transformed to give the mass. The key feature of this machine is that, at the turning points, a cation may encounter an anion when they are both nearly at rest. This condition is most favorable for promoting electron transfer. Furhtermore, fragment ions are then born with the correct kinetic energy so that the pick-up electrode can obtain their mass accurately from their oscillation frequency. In addtion, the apparatus features several innovative features and a high-transmission electrospray ion source as well as an electron-impact molecular beam ion source.