Abstract: An electrostatic ion trap confines ions of different mass to charge ratios and kinetic energies within an anharmonic potential well. The ion trap is also provided with a small amplitude AC drive that excites confined ions. The mass dependent amplitudes of oscillation of the confined ions are increased as their energies increase, due to an autoresonance between the AC drive frequency and the natural oscillation frequencies of the ions, until the oscillation amplitudes of the ions exceed the physical dimensions of the trap, or the ions fragment or undergo any other physical or chemical transformation.

Abstract: An electrostatic ion trap confines ions of different mass to charge ratios and kinetic energies within an anharmonic potential well. The ion trap is also provided with a small amplitude AC drive that excites confined ions. The mass dependent amplitudes of oscillation of the confined ions are increased as their energies increase, due to an autoresonance between the AC drive frequency and the natural oscillation frequencies of the ions, until the oscillation amplitudes of the ions exceed the physical dimensions of the trap, or the ions fragment or undergo any other physical or chemical transformation.

Abstract: The inventive apparatus measures workfunction values using deflection of an electron beam without direct contact of the electron beam with the sample surface. The apparatus, mounted within a vacuum chamber, includes an electron gun, a position sensitive electron detector, and a sample. The sample is located such that an electron beam emanating from the gun can approach the surface and then be deflected into the position sensitive electron detector. Workfunction values are then derived from a measured deflected-electron position distribution.