Abstract: Apparatus and methods for performing charge detection mass spectrometry for measurement of the mass of a single ion of interest are disclosed. The ion of interest is caused to undergo harmonic oscillatory movement in the trapping field of an electrostatic trap, such that an image current detector generates a time-varying signal representative of the ion's oscillatory movement. This time-varying signal (transient) is processed (e.g., via a Fourier transform) to derive the ion's frequency and consequently determine the ion's mass-to-charge ratio (m/z). Ion charge is determined by construction of a Selective Temporal Overview of Resonant Ion (STORI) plot, which tracks the temporal evolution of signals attributable to the ion of interest, and where the slope of the STORI plot is related to the charge. The STORI plot may also be employed to identify ion decay events during transient acquisition and/or the presence of multiple ions of the same mass or non-resolvable ions.

Abstract: A high resolution Fourier Transform Ion Cyclotron Resonance (FT-ICR) mass spectrometry system includes excitation circuitry including an excitation amplifier for generating an electrical excitation signal and excitation electrodes for applying an oscillating electric field to excite ions in the system. Detection circuitry including detection electrodes measures a detection signal which includes a plurality of signal values including signal values induced by the ions. Structure is provided for reducing or canceling coupling of the excitation signal into the detection signal, wherein simultaneous excitation and detection is used. A computing structure generates a Fourier transformed frequency domain representation of the detection signal and deconvolves the frequency domain representation using complex division to separate a dispersion spectrum portion and an absorption spectrum portion.

Abstract: The ionization efficiency of a mass spectrometer is increased by creating a potential well between the electron source and the electron collector. The potential well is created by applying to the collector a reflection potential having an amplitude which is the same as or substantially the same as the amplitude of the potential applied to the electron source and a polarity which is the same as the polarity of the electron source potential. The potentials applied to the electron source and electron collector are relative to the ionization region effected between the source and collector. Many of the electrons produced by the electron source oscillate back and forth in the potential well thereby allowing those electrons a greater opportunity to interact with sample molecules to thus increase ionization efficiency.

Abstract: The total number of ions created br obtained during an ionization or ion introduction event in a Fourier transform ion cyclotron resonance mass spectrometer are determined either by using an on-resonance experimental technique or an off-resonance experimental technique. Both techniques exploit ion magnetron motion. In the on-resonance technique the spectrometer is excited in the magnetron mode and the single resonance signal resulting from this excitation is detected to determine the total number of ions. In the off-resonance technique the magnetron mode is excited at a frequency that is near the magnetron frequency while simultaneously detecting the resulting ion motion. The off-resonance technique leaves the ion population in a state that is amenable to subsequent analysis.