Prospect of increasing secondary ion yields in ToF‐SIMS using water cluster primary ion beams

Sheraz, Sadia; Barber, A.; Razo, Irma Berrueta; Fletcher, John S.; Lockyer, Nicholas P.; Vickerman, John C.

doi:10.1002/sia.5606

Cited by 24 publications

(17 citation statements)

References 13 publications

(35 reference statements)

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“…Previously for instrumental reasons, negative ion detection was not available. 30,31 However, perhaps naively, we did not expect negative ion enhancement having focused on the possibility of enhanced proton attachment to molecules. Just by comparing the spectra, it can be seen that negative ion enhancement for molecularly related ions is as great if not greater than that for positive ions.…”

Section: ■ Results and Discussionmentioning

confidence: 97%

Enhanced Ion Yields Using High Energy Water Cluster Beams for Secondary Ion Mass Spectrometry Analysis and Imaging

et al. 2019

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Previous studies have shown that the use of a 20 keV water cluster beam as a primary beam for the analysis of organic and bio-organic systems resulted in a 10−100 times increase in positive molecular ion yield for a range of typical analytes compared to C 60 and argon cluster beams. This resulted in increased sensitivity to important lipid molecules in the bioimaging of rat brain. Building on these studies, the present work compares 40 and 70 keV water cluster beams with cluster beams composed of pure argon, argon and 10%CO 2 , and pure CO 2 . First, as previously, we show that for E/nucleon about 0.3 eV/nucleon water and nonwater containing cluster beams generate very similar ion yields, but below this value, the water beams yields of BOTH negative and positive "molecular" ions increase, in many cases reaching a maximum in the <0.2 region, with yield increases of ∼10−100. Ion fragment yields in general decrease quite dramatically in this region. Second, for water cluster beams at a constant E/nucleon, "molecular" ion yield increases with beam energy and hence cluster size due to increased sputter yield (ionization probability is constant). Third, as a consequence of the increased ion yield and the improved focusability using high-energy cluster beams, imaging in the 1 μm spatial resolution region is demonstrated on HeLa cells and rat brain tissue, monitoring molecules that were previously difficult to detect with other primary beams. Finally, the suggestion that the secondary ion emission zone has quasi-aqueous character seems to be sustained.

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Section: ■ Results and Discussionmentioning

confidence: 97%

Enhanced Ion Yields Using High Energy Water Cluster Beams for Secondary Ion Mass Spectrometry Analysis and Imaging

et al. 2019

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“…8,9,[18][19][20] The results indicate that in the singlecomponent samples, the ionization of both molecules is enhanced with the (H 2 O) n þ ion beam, particularly with larger water clusters (Fig. 2).…”

Section: A Analysis Of Single-component Samplesmentioning

confidence: 89%

“…As with the pure samples, the [MþH] þ yields of both analytes in the mixture were enhanced when analyzed with water ion beams, although the cluster size appears less significant in determining the ion yield. Arginine is enhanced by a factor of 4 using a water beam, whereas histidine is enhanced by a factor of 8 Figure 4 shows the result of analyzing different arginine:-histidine mixture ratios with different ion beams. In a quantitative analysis it is convenient if the yield ratio of the [MþH] þ ions is linearly dependent on the mole ratio of components.…”

Section: A Analysis Of Single-component Samplesmentioning

confidence: 99%

“…Different polyatomic ion beams can be utilized in SIMS analysis and can have a remarkable effect on secondary ion yield. 7,8 Water-based ion beams (H 2 O) n þ of different cluster sizes show a significantly enhanced [MþH] þ yield compared to Ar n þ of a similar cluster size or energy/nucleon. This can be explained as the water cluster facilitating proton donation in the emission zone.…”

Section: Introductionmentioning

confidence: 99%

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Matrix effects in biological SIMS using cluster ion beams of different chemical composition

2016

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The influence of the matrix effect on secondary ion yield presents a very significant challenge in quantitative secondary ion mass spectrometry (SIMS) analysis, for example, in determining the relative concentrations of metabolites that characterize normal biological activities or disease progression. Not only the sample itself but also the choice of primary ion beam may influence the extent of ionization suppression/enhancement due to the local chemical environment. In this study, an assessment of ionization matrix effects was carried out on model systems using C60+, Arn+, and (H2O)n+ cluster ion beams. The analytes are pure and binary mixtures of amino acids arginine and histidine biological standards. Ion beams of 20 keV were compared with a range of cluster sizes n = 1000–10 000. The component secondary ion yields were assessed for matrix effects using different primary ion beams and sample composition. The presence of water in the cluster beam is associated with a reduction in the observed matrix effects, suggesting that chemically reactive ion beams may provide a route to more quantitative SIMS analysis of complex biological systems.

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“…To increase absolute molecular yields and the associated chemical sensitivity, cluster beams were introduced in SIMS, such as , , , and clusters with n = 55–3000 [ 32 , 33 ]. More recently, the use of water clusters in SIMS has been demonstrated to improve both aspects even further [ 34 , 35 ].…”

Section: Introductionmentioning

confidence: 99%

Molecular imaging of humain hair with MeV-SIMS: A case study of cocaine detection and distribution in the hair of a cocaine user

et al. 2022

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Human hair absorbs numerous biomolecules from the body during its growth. This can act as a fingerprint to determine substance intake of an individual, which can be useful in forensic studies. The cocaine concentration profile along the growth axis of hair indicates the time evolution of the metabolic incorporation of cocaine usage. It could be either assessed by chemical extraction and further analysis of hair bundels, or by direct single hair fibre analysis with mass spectroscopy imaging (MSI). Within this work, we analyzed the cocaine distribution in individual hair samples using MeV-SIMS. Unlike conventional surface analysis methods, we demonstrate high yields of nonfragmented molecular ions from the surface of biological materials, resulting in high chemical sensitivity and non-destructive characterisation. Hair samples were prepared by longitudinally cutting along the axis of growth, leaving half-cylindrical shape to access the interior structure of the hair by the probing ion beam, and attached to the silicon wafer. A focused 5.8 MeV 35Cl6+ beam was scanned across the intact, chemically pristine hair structure. A non-fragmented protonated [M+ H]+ cocaine molecular peak at m/z = 304 was detected and localized along the cross-section of the hair. Its intensity exhibits strong fluctuations along the direction of the hair’s growth, with pronounced peaks as narrow as 50 micrometres, corresponding to a metabolic incorporation time of approx. three hours.

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Prospect of increasing secondary ion yields in ToF‐SIMS using water cluster primary ion beams

Cited by 24 publications

References 13 publications

Enhanced Ion Yields Using High Energy Water Cluster Beams for Secondary Ion Mass Spectrometry Analysis and Imaging

Enhanced Ion Yields Using High Energy Water Cluster Beams for Secondary Ion Mass Spectrometry Analysis and Imaging

Matrix effects in biological SIMS using cluster ion beams of different chemical composition

Molecular imaging of humain hair with MeV-SIMS: A case study of cocaine detection and distribution in the hair of a cocaine user

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