An optimised compact electron impact ion storage source for a time-of-flight mass spectrometer

Abplanalp, D.; Würz, Peter; Huber, L.; Leya, I.

doi:10.1016/j.ijms.2010.05.001

Cited by 22 publications

(7 citation statements)

References 8 publications

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“…The repetition frequency of the pulser can be adjusted (≤10 kHz; rise time, approximately 4.6 ns) for optimal measurement conditions. Note that the lower the pulse frequency, the more ions can be stored in the ion source . However, a longer storage time of the ions in the source region can also result in unwanted nonlinear effects, ie, detector saturation, sensitivities, or fractionation factors that depend on the gas amounts.…”

Section: Methodsmentioning

confidence: 99%

EGT—A sensitive time‐of‐flight mass spectrometer for multielement isotope gas analysis

et al. 2018

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The principles of operation and figures of merit of a novel, compact (324 mm × Ø 114 mm; volume approximately 1000 cm ) reflectron-type time-of-flight mass spectrometer designed for simultaneous multielement isotope gas analysis is presented. The system, which consists of a pulsed electron impact ion source, is designed either to directly analyse gas samples collected and stored in a compartment or samples extracted from solids using a CW laser system (fibre-coupled diode laser, <75 W, λ = 808 ± 10 nm). In latter case, laser pulses are focussed onto the sample surface to spot sizes of approximately 400 μm in diameter that allows for direct ablation and vaporisation of solid sample material and releasing of trapped gases. A cleaning and trapping system that consists of various cold stages and getters is used before the gas enters the mass analyser. Measurements on various gases were conducted for performance evaluation, ranging from standard gases (Ar, Kr, and Xe) to trapped gases extracted from a sample of the Millbillillie meteorite. At optimised instrument settings, mass spectrometric measurements can be conducted with a mass resolution m/∆m of up to approximately 1200 ( O and CH can be resolved), with a dynamic range of approximately 6 orders of magnitude and a mass calibration accuracy of approximately 100 ppm. The high detection sensitivity of the system allows the detection of gas species at partial pressures down to the low 10 mbar level (corresponding to <10 particles/cm at standard temperature and pressure, including an ion transmission of approximately 80%). Measurements using standard gases demonstrated that the isotope ratios for a given element can be measured with an accuracy at the per mill level (relative to terrestrial values). Measurements of Ar extracted from the meteorite Millbillillie gave a Ar/ Ar ratio of approximately 1.6, which is in good agreement with literature values.

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Section: Methodsmentioning

confidence: 99%

EGT—A sensitive time‐of‐flight mass spectrometer for multielement isotope gas analysis

et al. 2018

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“…In this work, the mesh has a pitch of 0.2 mm and the mesh wires have a circular cross-section, with a diameter of 0.0127 mm. While it has been known for some time that meshes can give rise to fringe effects and local field distortions [18][19][20][21][22][23][24], it is still rare to see the mesh region of an experimental set-up explicitly described in simulations. While the optical transmission of a mesh is often considered, it is otherwise usually treated as a featureless plane or ideal grid in simulations carried out using software packages such as SIMION.…”

Section: Simulationsmentioning

confidence: 99%

Fringe fields are important when examining molecular orientation in a cold ammonia beam

Heazlewood¹,

Bertier²

2021

J. Phys. B: At. Mol. Opt. Phys.

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External fields have been widely adopted to control and manipulate the properties of gas-phase molecular species. In particular, electric fields have been shown to focus, filter and decelerate beams of polar molecules. While there are several well-established approaches for controlling the velocity and quantum-state distribution of reactant molecules, very few of these methods have examined the orientation of molecules in the resulting beam. Here we show that a buffer gas cell and three-bend electrostatic guide (coupled to a time-of-flight set-up) can be configured such that 70% of ammonia molecules in the cold molecular beam are oriented to an external electric field at the point of detection. With a minor alteration to the set-up, an approximately statistical distribution of molecular orientation is seen. These observations are explained by simulations of the electric field in the vicinity of the mesh separating the quadrupole guide and the repeller plate. The combined experimental apparatus therefore offers control over three key properties of a molecular beam: the rotational state distribution, the beam velocity, and the molecular orientation. Exerting this level of control over the properties of a molecular beam opens up exciting prospects for our ability to understand what role each parameter plays in reaction studies.

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“…The helical electron path increases the neutral−electron interaction time to improve ionization efficiency and generates a weak space-charge potential well that stores ions (storage ion source), improving source sensitivity. 50 To extract the ions into the TOF analyzer, we apply two independent, fast, push/pull pulses (∼5 ns rise-time for 3 μs) to energize the pusher grid with a more positive voltage relative to the extractor grid and provide constant energy per charge acceleration. The ion packet is accelerated out of the ion source and a series of beam defining optics guides the ions into the mass analyzer.…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

Experimental Coupling of a MEMS Gas Chromatograph and a Mass Spectrometer for Organic Analysis in Space Environments

Libardoni

Miller

et al. 2020

ACS Earth Space Chem.

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The mass spectrometer for planetary exploration (MASPEX) is a versatile mass spectrometer with unprecedented mass resolution designed for spaceflight. However, the current version of MASPEX is designed for continuous sampling during flybys of planetary bodies and does not include gas chromatography, which can improve the analysis of complex mixtures of organic compounds in space environments. Here, micro-electro-mechanical system (MEMS) gas chromatography (GC) linearity, reproducibility, and column analytical performance were first demonstrated prior to the coupling to MASPEX for MEMS GC−mass spectrometer (MS) analyses. Linearity of response was demonstrated for n-hexane over 2 orders of magnitude of on-column mass (concentration). Retention time reproducibility in the MEMS GC was ≤2% relative standard deviation (RSD). MEMS GC column analytical performance calculations showed the average number of theoretical plates, N, and the height equivalent to a theoretical plate, HETP, to be 16 239 (1623 plates per meter) and 0.062 cm, respectively. N defines a chromatographic centroid peak apex divided by the peak width at half height, similar to mass resolution. When coupled to MASPEX, the retention time reproducibility was in a similar range of 1−2% relative standard deviation with a slightly larger deviation seen from the mass spectrometer detector due to start trigger variations with a manual start trigger in the FastFlight software compared to the LabView code used for the MEMS GC−MS testing. The collected mass spectra showed close consistency with National Institute of Standards and Technology (NIST) reference mass spectra providing confidence in chemical compound identification. We present the first data generated from the coupling of these devices.

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An optimised compact electron impact ion storage source for a time-of-flight mass spectrometer

Cited by 22 publications

References 8 publications

EGT—A sensitive time‐of‐flight mass spectrometer for multielement isotope gas analysis

EGT—A sensitive time‐of‐flight mass spectrometer for multielement isotope gas analysis

Fringe fields are important when examining molecular orientation in a cold ammonia beam

Experimental Coupling of a MEMS Gas Chromatograph and a Mass Spectrometer for Organic Analysis in Space Environments

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