Analysis of polymer surfaces by SIMS 17. An assessment of the accuracy of the mass assignment using a high mass resolution ToF‐SIMS instrument

Reichlmaier, S.; Hammond, John S.; Hearn, M. J.; Briggs, D.

doi:10.1002/sia.740211102

Cited by 45 publications

(37 citation statements)

References 13 publications

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“…maier et al [6] clearly demonstrate the need for sufficient counts in a peak for accurate mass assignment. They conclude that Ͼ1000 counts are required for W Ͻ10 ppm and that, over the range 0 -600 u, 20 ppm is achievable and, with care, Ͻ10 ppm is possible.…”

mentioning

confidence: 99%

“…Reichlmaier et al [6] conducted a detailed assessment of the accuracy of mass scale calibration and of the repeatability over a period of 6 months. They used a PHI 7210 TOF spectrometer with a two stage reflection energy compensator to study the effect of calibration with different sets of ions on both the average mass accuracy and the repeatability over 34 spectra recorded in that period.…”

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confidence: 99%

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TOF-SIMS: Accurate mass scale calibration

Green

Gilmore

Seah

2006

J. Am. Soc. Mass Spectrom.

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A study is presented of the factors affecting the calibration of the mass scale in time-of-flight secondary ion mass spectrometry (TOF-SIMS). At the present time, TOF-SIMS analysts using local calibration procedures achieve a rather poor relative mass accuracy of only 150 ppm for large molecules (647 u) whereas for smaller fragments of Ͻ200 u this figure only improves to 60 ppm. The instrumental stability is 1 ppm and better than 10 ppm is necessary for unique identification of species. The above experimental uncertainty can lead to unnecessary confusion where peaks are wrongly identified or peaks are ambiguously assigned. Here we study, in detail, the instrumental parameters of a popular single stage reflection TOF-SIMS instrument with ion trajectory calculations using SIMION. The effect of the ion kinetic energy, emission angle, and other instrumental operating parameters on the measured peak position are determined. This shows clearly why molecular and atomic ions have different relative peak positions and the need for an aperture to restrict ions at large emission angles. These data provide the basis for a coherent procedure for optimizing the settings for accurate mass calibration and rules by which calibrations for inorganics and organics may be incorporated. This leads to a new generic set of ions for mass calibration that improves the mass accuracy in our interlaboratory study by a factor of 5. A calibration protocol is developed, which gives a relative mass accuracy of better than 10 ppm for masses up to 140 u. The effects of extrapolation beyond the calibration range are discussed and a recommended procedure is given to ensure that accurate mass is achieved within a selectable uncertainty for large molecules. Additionally, we can alternatively operate our instrument in a regime with good energy discrimination (i.e., poor energy compensation) to study the fragmented energies of molecules. This leads to data that support previous concepts developed in G-SIMS. tatic SIMS (SSIMS) is a powerful technique for the analysis of organic and molecular surfaces. Over the last decade, instrumentation has improved significantly so that modern instruments now have very high reliability. Together with reference procedures and methods, the intensity repeatability has improved by over a factor of 10. In a recent VAMAS interlaboratory study [1] conducted by NPL, over 84% of instruments exhibited excellent intensity repeatabilities of better than 1.9%. It was also demonstrated that the comparability of relative ion intensities between different instrument designs can be Ͻ4% by incorporation of the concept of the relative instrument spectral response (RISR) function [1].A significant issue for many analysts is establishing an accurate calibration of the mass scale for time-of-flight (TOF) instruments. In a recent ISO [2] survey of needs for standardization in static SIMS, analysts ranked a procedure for mass calibration as the top priority. Typically, this needs to be conducted for each spectrum since small variations in t...

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mentioning

confidence: 99%

mentioning

confidence: 99%

TOF-SIMS: Accurate mass scale calibration

Green

Gilmore

Seah

2006

J. Am. Soc. Mass Spectrom.

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“…The resolution is m/Am = 7500 at mlz = 29 and m/m = loo00 at m/z = 119. 16 A flood gun (< 200 ev) was used for effective charge compensation. The depth profile and imaging SIMS experiments were carried out using a VG Scientific SIMSlab quadrupolebased mass spectrometer at MATS UK Ltd.…”

Section: Methodsmentioning

confidence: 99%

SIMS Investigation of Fresh and Aged Automotive Exhaust Catalysts

Oakes¹,

Vickerman²

1996

Surf. Interface Anal.

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“…The assignment of a specific structure and/or formula is thought to be exact when  is no bigger than a few parts per million. 12 Along with the typical analysis, we performed a depth profile using the beam to etch the surface in a continuous non-pulsed mode for times varying between 5 s and 5 min. The set-up of the depth profile analysis is shown in Fig.…”

Section: Time-of-flight Secondary Ion Mass Spectroscopy (Tof-sims) Anmentioning

confidence: 99%

“…In the case of pure aluminium analysis, the same conditions and parameters were used. The accuracy of mass assignment,  (in ppm), is calculated as follows 12,13 …”

Section: Time-of-flight Secondary Ion Mass Spectroscopy (Tof-sims) Anmentioning

confidence: 99%