Quantitative Surface Analysis of a Binary Drug Mixture—Suppression Effects in the Detection of Sputtered Ions and Post-Ionized Neutrals

Karras, G.; Lockyer, Nicholas P.

doi:10.1007/s13361-014-0847-6

Cited by 11 publications

(10 citation statements)

References 42 publications

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“…61 Other approaches for semi-quantitative analysis include metal-assisted SIMS (MetA-SIMS), where a thin metal is deposited on top of the material under analysis, 62,63 analysis of prominent ion signals from metallic cations, 64,65 and laser post-ionization. 66,67 The large size of ToF-SIMS datasets can complicate analysis. ToF-SIMS datasets can include threedimensional spatial information and high-resolution mass spectra, similar to hyperspectral image maps.…”

Section: Challenges In Tof-sims Data Analysismentioning

confidence: 99%

“…In a follow up study, Shard et al used an empirical expression to model the variations in secondary ion intensities as a function of the volume fraction of each component in a binary blend and defined a parameter to quantify the sign and magnitude of the matrix effect in blends 61 . Other approaches for semi‐quantitative analysis include metal‐assisted SIMS (MetA‐SIMS), where a thin metal is deposited on top of the material under analysis, 62,63 analysis of prominent ion signals from metallic cations, 64,65 and laser post‐ionization 66,67 …”

Section: Overview Of Tof‐simsmentioning

confidence: 99%

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Characterization of polymeric surfaces and interfaces using time‐of‐flight secondary ion mass spectrometry

Mei

Laws

Terlier

et al. 2021

Journal of Polymer Science

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Time-of-flight secondary ion mass spectrometry (ToF-SIMS) is used for chemical analysis of surfaces. ToF-SIMS is a powerful tool for polymer science because it detects a broad mass range with good mass resolution, thereby distinguishing between polymers that have similar elemental compositions and/or the same types of functional groups. Chemical labeling techniques that enhance contrast, such as deuterating or staining one constituent, are generally unnecessary. ToF-SIMS can generate both two-dimensional images and three-dimensional depth profiles, where each pixel in an image is associated with a complete mass spectrum. This Review begins by introducing the principles of ToF-SIMS measurements, including instrumentation, modes of operation, strategies for data analysis, and strengths/limitations when characterizing polymer surfaces. The sections that follow describe applications in polymer science that benefit from characterization by ToF-SIMS, including thin films and coatings, polymer blends, composites, and electronic materials. The examples selected for discussion showcase the three standard modes of operation (spectral analysis, imaging, and depth profiling) and highlight practical considerations that relate to experimental design and data processing. We conclude with brief comments about broader opportunities for ToF-SIMS in polymer science.

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Section: Challenges In Tof-sims Data Analysismentioning

confidence: 99%

Section: Overview Of Tof‐simsmentioning

confidence: 99%

Characterization of polymeric surfaces and interfaces using time‐of‐flight secondary ion mass spectrometry

Mei

Laws

Terlier

et al. 2021

Journal of Polymer Science

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“…These effects lead to major uncertainties in determining layer thicknesses and sputtering rates from the intensity profiles. The effects arise from matrix enhancement and suppression of the intensities arising from the juxtaposition of the atoms of different materials . Where peaks occur at an organic interface, they usually arise from strong matrix enhancement.…”

Section: Introductionmentioning

confidence: 99%

SIMS of organic layers with unknown matrix parameters: Locating the interface in dual beam argon gas cluster depth profiles

Havelund

Seah

Gilmore

2019

Surface & Interface Analysis

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Four simple methods are evaluated to determine their accuracies for establishing the interface location in secondary ion mass spectrometry intensity depth profiles of organic layers where matrix effects have not been measured. Accurate location requires the separate measurement of each ion's matrix factor. This is often not possible, and so estimates using matrix‐less methods are required. Six pure organic material interfaces are measured using many secondary ions to compare their locations from the four methods with those from full evaluation with matrix terms. For different secondary ions, matrix effects cause the apparent interface positions to vary over 20 nm. The shifts in the intensity profiles on going from a layer of P into a layer of Q are in the opposite direction to that for going from Q into P, so doubling layer thickness errors. The four methods are as follows: M1, use of the median interface position in the intensity profiles for the five lightest ions for 15 ≤ m/z ≤ 150; M2, extrapolation of the position for each ion to m/z = 0 for ions with m/z ≤ 150; M3, as M2 but for m/z ≤ 300; and M4, the extreme positions for all m/z ≤ 100. Comparison with the location using matrix terms shows their ranking, from best to worst, to be M4, M3, M1, and M2 with average errors of 10%, 12%, 14%, and 17%, respectively, of the profile interface full widths at half maximum. Use of pseudo‐molecular ions is very much poorer, exceeding 50%, and should be avoided.

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“…A possible strategy to photoionize sputtered molecules without photofragmentation is via strong field photoionization in the near‐infrared wavelength range . This method has been shown to permit the intact ionization of many organic molecules . In these experiments, the post‐ionization process is decoupled from the emission, so that sputtered neutral molecules are detected with constant efficiency regardless of the momentary surface chemistry.…”

Section: Introductionmentioning

confidence: 99%

Effect of SIMS ionization probability on depth resolution for organic/inorganic interfaces

Popczun

Breuer

Wucher

et al. 2017

Surf Interface Anal

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Secondary ion mass spectrometry (SIMS) relies on the fact that surface particles ejected from a solid surface are ionized under ion bombardment. By comparing the signal of molecular secondary ions desorbed from an organic film with that of the corresponding sputtered neutral precursor molecules, we investigate the variation of the molecular ionization probability when depth profiling through the film to the substrate interface. As a result, we find notable variations of the ionization probability both at the original surface and in the interface region, leading to a strong distortion of the measured SIMS depth profile. The experiments show that the effect can act in two ways, leading either to an apparent broadening or to an artificial sharpening of the observed film-substrate transition. As a consequence, we conclude that care must be taken when assessing interface location, width, or depth resolution from a molecular SIMS depth profile.

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Quantitative Surface Analysis of a Binary Drug Mixture—Suppression Effects in the Detection of Sputtered Ions and Post-Ionized Neutrals

Cited by 11 publications

References 42 publications

Characterization of polymeric surfaces and interfaces using time‐of‐flight secondary ion mass spectrometry

Characterization of polymeric surfaces and interfaces using time‐of‐flight secondary ion mass spectrometry

SIMS of organic layers with unknown matrix parameters: Locating the interface in dual beam argon gas cluster depth profiles

Effect of SIMS ionization probability on depth resolution for organic/inorganic interfaces

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