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The phase between the ion excitation and the image current measurement typically needs to be well controlled for obtaining high quality spectra. −, Z, where ν The model accommodates arbitrary electrode geometry, magnetic field inhomogeneity, ion-neutral collisions, and swept or single-frequency excitation, but does not account for ion–ion or ion–image charge forces. The distribution of gas flow field (velocity, pressure, temperature) was simulated by a 2D geometry. One or two pairs of sidebands occur symmetrically disposed about the peak, with their frequency offsets directly proportional to the square root of the trapping voltage, as expected from theory. The effects of trapping voltage, trap size and shape, and other nonidealities are manifested mainly as perturbations that preserve the idealized ion behavior modified by appropriate numerical correction factors. Its presence is manifested primarily by the appearance of even-numbered harmonics in the spectra. The results showed that the coupled field simulation model can be used to study parameters effects on the IMS. The efficiency of injecting and trapping ions from an external ion source in a quadrupole ion trap mass spectrometer was measured and compared against a simulation employing a simple hard-sphere collision model. By probing the effect of ion number and orbital radius on the shift in the cyclotron frequency, it is shown that for a monoisotopic population of ions, the frequency shift is caused by the interaction of ions with their image-charge. The temporal effects of ion evaporation and ion relaxation along the z-axis (parallel to the magnetic field) on ion signal intensity are addressed in this paper. International Journal of Mass Spectrometry, https://doi.org/10.1016/j.ijms.2009.02.009. Electrostatic Axially Harmonic Orbital Trapping: A High-Performance Technique of Mass Analysis, Combined Electron Capture and Infrared Multiphoton Dissociation for Multistage MS/MS in a Fourier Transform Ion Cyclotron Resonance Mass Spectrometer, Broadband Phase Correction of FT-ICR Mass Spectra via Simultaneous Excitation and Detection, Coaxial multi-electrode cell ('O-trap') for high-sensitivity detection at a multiple frequency in Fourier transform ion cyclotron resonance mass spectrometry: Main design and modeling results. With the new design, an ambient aerosol concentration (dN/dlog dm) of 1 × 103 cm−3 yields approximately 2–3 particles analyzed per minute. We also describe a custom differential amplifier to exploit the near-differential input to improve the signal-to-noise-ratio of the measured image charge. Here, = -200000, = -2000, = 100, = 1000 eV, and = 0. The magnitude of the ion cyclotron resonance (ICR) time-domain signal detected from the oscillating differential charge induced on opposed detector electrodes depends on the number, ICR orbital and magnetron radii, and phase coherence of the trapped ions. The ions trajectories and ion mobility spectra of the IMS were then calculated. Fourier transform ion cyclotron resonance mass spectrometry is evaluated in trapped ion cells which substitute open rectangular trapping electrodes for trapping plates positioned perpendicular to the magnetic field. A version of the ion trap simulation program, itsim, which accounts for the effects of ion/molecule collisions, is applied to show that this motion is remarkably stable even in the presence of bath gas. +, ν Comparison of simulated performance characteristics of the new O-trap with those of the same-size conventional cylindrical cell shows that the O-trap can provide higher sensitivity and ion capacity. We use cookies to help provide and enhance our service and tailor content and ads. Practical aspects of the trap design are presented. This article is a reflective overview of the origins, history, and capabilities of the ion optics simulation program SIMION for the PC (versions 2.0 -7.0) from the author's perspective. Phase coherence and shifts in the center of the ICR orbit are much more easily visualized in the new rotating-frame representation. Consequently, a magnetron orbit diameter can increase or decrease during a resonant cyclotron excitation. International Journal of Mass Spectrometry and Ion Processes. The sideband structure is analyzed and the origin of the sidebands is tracked. The latter is also commonly called Fourier transform MS (FT-MS). Finally, ion trajectories during on- and off-resonance single-frequency excitation are displayed in the usual fixed laboratory coordinate frame as well as in a coordinate frame rotating about the z-axis at the ICR orbital frequency of that ion. Simulations and experiments on the motion of collections of ions show that impulsive excitation, applied in the axial direction, forces ions into coherent motion with characteristic secular frequencies. For example, if in geometry A for r 0 = 101.6 mm we instead use R 1 = 72.4 0.1 = 72.3 gu and R 2 = 130.8 1+0.1 = 129.9 gu in the SIMION geometry file, we obtain a SIMION FE r = 12.4 u 10 4 , which is much smaller in magnitude than the FE r = 84.3u 10 4 We show experimentally several features of dynamic ion trapping in the open cell: (a) ions can be selectively trapped in different regions of the cell, (b) mass selective accumulation of ions can be performed inside the trapping cylinder, (c) ions can be sequentially, Instruments that trap ions in a magnetic and/or electric field play a very important role in the analysis of biomolecules. In the NAMS, charged nanoparticles pass through an aerodynamic lens, digital ion guide (DIG) and field adjusting lens (FAL) prior to entering a digital ion trap (DIT) where they are captured and subsequently analyzed. A new FAL assembly was designed to increase the number of trapped particles. Modeling Typical GEM files for sperical capacitors are given below. The ions are assumed to move in the central region of the trap where the harmonic approximation holds. Ion compression, accomplished by steadily increasing the trap voltage, is introduced as a means of expediting z-axis relaxation so that temporal variations of signal due to relaxation phenomena can be minimized. Experimental results agree qualitatively with theoretical predictions. The resonances at ω+ + 2ωz and near 2ωz show a decrease in the signal due to z-axis ejection. −, ν −ν z Rather a cylindrical energy filter was installed to remove the ions with undesired energies. Selection rules are developed for a class of detection schemes that will detect selected harmonics. Other envisioned benefits are improved descriptions of ion RF excitation and transient generation processes, as well as of an influence of a space-charge and of an image charge fields. It provides insight into the rationale and events that contributed to the direction of the evolution and current capabilities of the program. Currently, TOF instruments use pulsed ion introduction with a 10 ns or so pulse width, followed by a waiting period roughly 100 μs. The results are applied to obtain explicit expressions for several cases of practical interest. The amplitude-dependent frequencies of nonlinear oscillations become time dependent due to the collisional damping of oscillation amplitudes. We examine the “true” magnitude excitation spectrum, obtained by zero-filling and forward Fourier transforming the SWIFT time-domain waveform, in order to evaluate the trade-off between spectral magnitude uniformity and frequency (mass) selectivity. © 2008-2020 ResearchGate GmbH. Here, we review the principles, variations, algorithms, hardware implementation, and some applications of SWIFT for both ICR and quadrupole ion trap mass spectrometry.We show that the most desirable SWIFT waveform is that optimized to reduce both the time-domain SWIFT maximum amplitude and the amplitude near the start and end of the SWIFT waveform. A Fourier-transform mass spectrometric technique for detecting ion cyclotron resonance signals at multiple cyclotron frequencies is proposed and initial experimental results are presented. Future efforts will be aimed at building and testing experimentally the coaxial O-trap, including optimization of the method of ion transfer between the compartments of the cell. We find that resonant (single-frequency or frequency-sweep) electric field excitation not only increases the ICR orbital radius, but also induces an oscillating (for linearly polarized excitation) or rotating (for circularly polarized excitation) shift in the center of the ion cyclotron orbit of the ion packet (i.e. The device relies on voltages applied to the electrodes to establish symmetrically opposing ion focusing mirrors for the purpose of cycling ions through the charge detection tube many times. transferred between different regions of the cell, and (d) both positive and negative ions may be trapped and detected simultaneously. An ion cyclotron resonance (ICR) absorption spectrum has been obtained by exciting an ICR spectral segment with a fixed-frequency electric field pulse, followed by broad-band detection, digitization of the (time-domain) transient response, and digital Fourier transformation to produce the (frequency-domain) absorption spectrum. It has also been explored as a non-destructive mass analysis method using quadrupole ion traps. Further, if the cyclotron orbit is displaced radially (i.e., non-zero magnetron radius, as typically results from ion injection from an external source and/or from frequency-sweep excitation [31] ) image charge modeling predicts both odd and even harmonic signals ( Fig. The analytical frequency shifts agree very well with frequency shifts obtained from numerical trajectory calculations using the exact classical equations of motion. This review offers an introduction to the principles and generic applications of FT-ICR mass spectrometry, directed to readers with no prior experience with the technique. Comparisons are made with experimental data on ion motion, specifically with data obtained on ion motion using the d.c.-pump/laser-probe method, and with results of spatially- and temporally-resolved laser tomography experiments. These spectra yield resolving power improvement factors approaching the maximum theoretical limit of 2.0, as well as reduction in frequency assignment errors relative to conventional magnitude-mode spectra. electric field amplitude. In particular, multi-electrode detection at a multiple of the main cyclotron frequency can be utilized without the loss of sensitivity and other negative effects. In the present example, a signal-to-noise ratio of 8:1 and a mass resolution of about 0.005 amu for CH4+ (from CH4 at a pressure of 8 X 10−7 torr) have been achieved, using a single data acquisition period of 25.6 msec. A close match to experimental behavior is observed. A new concept for time-of-flight (TOF) mass spectrometry is presented. ... For the conventional FT-ICR MS, the analytical and numerical studies predict presence of odd order harmonics and interharmonics of the reduced cyclotron and magnetron frequencies [14. The sum of the signals from all the electrodes contains harmonics of order Mk (k is an integer).

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