An investigation of enhanced secondary ion emission under Au<sub>n</sub><sup>+</sup>(n=1–7) bombardment

Nagy, Gabriella; Gelb, Lev D.; Walker, Amy V.

doi:10.1016/j.jasms.2005.01.024

Cited by 27 publications

(23 citation statements)

References 39 publications

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“…However, in the positive ion mass spectrum the secondary ion yields for Bi 5 2ϩ are only ϳ20% of those observed for Bi 5 ϩ . The secondary ion yields for Bi 3 xϩ and Bi 5 xϩ are larger than for Bi xϩ (x ϭ 1, 2) in agreement with previous studies which show that the secondary ion yields increase with increasing number of primary ion constituent atoms [6,7,9,11,13]. However, the secondary ion yields for Bi 3 xϩ primary ion bombardment are in general larger than for Bi 5 xϩ .…”

Section: Secondary Ion Yields: Phenylalanine Dppc Dppe Cholesterolsupporting

confidence: 90%

“…However, the secondary ion yields for Bi 3 xϩ primary ion bombardment are in general larger than for Bi 5 xϩ . This is most likely due to the decrease in projectile velocity balancing the expected increase in the secondary ion yield attributable to the increase in the number of projectile constituent atoms (see [6,13] and references therein). We note that the secondary yield enhancements due to the doubly charged ions decrease with increasing primary ion constituent number; the yield enhancements are larger for Bi 2ϩ than Bi 3 2ϩ , which in turn are larger than for Bi 5 2ϩ primary ions.…”

Section: Secondary Ion Yields: Phenylalanine Dppc Dppe Cholesterolmentioning

confidence: 99%

“…The utility of SIMS has been greatly increased recently by the introduction of polyatomic primary ion beams [2,3]. Polyatomic projectiles, such as Bi n ϩ [4 -6] and Au n ϩ [7][8][9][10][11][12][13], have been demonstrated to greatly enhance molecular ion yields compared to monoatomic primary ions such as Ga ϩ or Ar ϩ . The use of polyatomic primary ions has also led to improvements in the useful lateral resolution of SIMS mass spectrometric (chemical) images [5].…”

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confidence: 99%

“…These materials have all been previously characterized by SIMS, and DL-phenylalanine, Irganox 1010, and PS were used in previous studies of secondary yield enhancements using Bi n ϩ [6] and Au n ϩ primary ions [7,8,11,13].…”

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An investigation of secondary ion yield enhancement using Bi_n²⁺ (n=1, 3, 5) primary ions

Nagy

Walker

2008

J. Am. Soc. Mass Spectrom.

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Section: Secondary Ion Yields: Phenylalanine Dppc Dppe Cholesterolsupporting

confidence: 90%

Section: Secondary Ion Yields: Phenylalanine Dppc Dppe Cholesterolmentioning

confidence: 99%

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confidence: 99%

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confidence: 99%

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An investigation of secondary ion yield enhancement using Bi_n²⁺ (n=1, 3, 5) primary ions

Nagy

Walker

2008

J. Am. Soc. Mass Spectrom.

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“…The organic signals will be significantly im- proved, for example, utilizing a C 60 [30,31], Bi cluster [32], or Au cluster source [33], and coupled with multivariate statistical techniques [34,35]. Such sources provide greater ionization efficiency and yields of larger and more indicative fragments [36].…”

Section: Discussionmentioning

confidence: 99%

Use of TOF-SIMS to study adsorption and loading behavior of methylene blue and papain in a nano-porous silicon layer

Kempson

Barnes

Prestidge

2010

J. Am. Soc. Mass Spectrom.

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TOF-SIMS was applied to study the cross-sectional distribution of methylene blue and papain in porous silicon layers. Elemental and molecular information were used to study their distributions in the porous region and the chemistry of their adsorption. Methylene blue (MW ϭ 284 Da) [4], and the delivery of active pharmaceutical ingredients [5,6]. The ongoing interest in pSi for use as a therapeutic delivery system is due to the large internal surface area available, the readily modified surface chemistry [7] and, in particular, the excellent in vivo biodegradation and biocompatibility (low toxicity) of the silicon substrate, hydrolysing to form orthosilicic acid, which is readily excreted [8]. The loading dynamics of molecules into a pSi matrix is dependent on wetting and the size of the pores. Likewise, the interaction between a loaded molecule and the pSi substrate is of interest, particularly in the case of protein based therapeutics, whose bioactivity is dependent on remaining in a specific 3D conformation.TOF-SIMS analysis provides information regarding elemental and molecular species present in a sample surface (i.e., within 1-1.5 nm) with high mass resolution (up to ϳ10,000 m/⌬m) and spatial resolution for imaging (ϳ1 micron). Molecular and elemental information is obtained for organic and inorganic materials providing a powerful technique to image organic compounds associated with inorganic substrates or vice versa [9,10]. This has been demonstrated by imaging solid-state pharmaceutical formulations [11][12][13][14], however, to date this has not been extended to porous silicon substrates.In this study, TOF-SIMS was used to map the distribution of methylene blue and papain across porous silicon layers after loading from aqueous solution. Methylene blue (C 16 H 18 N 3 S ϩ , MW ϭ 284.12 g/mol) is a relatively small organic dye molecule commonly used in adsorption studies and can be considered analogous to therapeutic molecules. A molecular mass of 284 g/mol is within a reasonable mass range for a TOF-SIMS' Ga ϩ primary ion beam and can be easily and uniquely identified without interference or confusion from spectral peaks originating from the silicon substrate or in the instance of organic contamination. This molecule was chosen for its convenience, and to assess the ability to use smaller organic fragments to reflect the distribution of the molecule of interest. This is important to be able to extend this work to studying larger molecules, such as proteins and enzymes of pharmaceutical interest, which will not provide a molecular ion in TOF-SIMS. In contrast to methylene blue, papain is a much larger molecule, detailed elsewhere [15], comprising 212 residue units in two domains, giving a molecular weight of 23,406 g/mol. Papain is a cysteine protease hydrolase enzyme present in papaya. This molecular weight is far greater than can be detected with TOF-SIMS, however, fragmentation products can be detected. Smaller organic fragments can be compared with the distribution of methylene blue to investigate si...

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Surface Analysis of Organic Materials with Polyatomic Primary Ion Sources

Mahoney

2013

Cluster Secondary Ion Mass Spectrometry

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An investigation of enhanced secondary ion emission under Au_n⁺(n=1–7) bombardment

Cited by 27 publications

References 39 publications

An investigation of secondary ion yield enhancement using Bi_n²⁺ (n=1, 3, 5) primary ions

An investigation of secondary ion yield enhancement using Bi_n²⁺ (n=1, 3, 5) primary ions

Use of TOF-SIMS to study adsorption and loading behavior of methylene blue and papain in a nano-porous silicon layer

Surface Analysis of Organic Materials with Polyatomic Primary Ion Sources

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An investigation of enhanced secondary ion emission under Aun+(n=1–7) bombardment

Cited by 27 publications

References 39 publications

An investigation of secondary ion yield enhancement using Bin2+ (n=1, 3, 5) primary ions

An investigation of secondary ion yield enhancement using Bin2+ (n=1, 3, 5) primary ions

Use of TOF-SIMS to study adsorption and loading behavior of methylene blue and papain in a nano-porous silicon layer

Surface Analysis of Organic Materials with Polyatomic Primary Ion Sources

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An investigation of enhanced secondary ion emission under Au_n⁺(n=1–7) bombardment

An investigation of secondary ion yield enhancement using Bi_n²⁺ (n=1, 3, 5) primary ions

An investigation of secondary ion yield enhancement using Bi_n²⁺ (n=1, 3, 5) primary ions