Molecular Depth Profiling with Cluster Ion Beams

Mahoney, Christine M.; Wucher, A.

doi:10.1002/9781118589335.ch5

Cited by 7 publications

(10 citation statements)

References 168 publications

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“…A unique aspect of cluster secondary ion mass spectrometry (SIMS) is the ability to depth profile through a molecular solid with chemical specificity. − There are systems for which depth profiling works well, such as trehalose, Irganox, cholesterol, Langmuir–Blodgett films, amino acids, and organic light emitting diodes (OLEDs) if the metal overlayer is delaminated first. Challenges do arise in depth profiling of some polymers and in heterogeneous systems, such as metal overlayers on organic solids , or prefabricated metal–organic systems .…”

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confidence: 99%

Computed Molecular Depth Profile for C₆₀ Bombardment of a Molecular solid

2013

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Molecular dynamics (MD) simulations have been performed for 10 keV C60 bombardment of an octane molecular solid at normal incidence. The results are analyzed using the steady-state statistical sputtering model (SS-SSM) to understand the nature of molecular motions and to predict a depth profile of a δ-layer. The octane system has sputtering yield of ~150 nm(3) of which 85% is in intact molecules and 15% is fragmented species. The main displacement mechanism is along the crater edge. Displacements between layers beneath the impact point are difficult because the nonspherically shaped octane molecule needs a relatively large volume to move into and the molecule needs to be aligned properly for the displacement. Since interlayer mixing is difficult, the predicted depth profile is dominated by the rms roughness and the large information depth because of the large sputtering yield.

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confidence: 99%

Computed Molecular Depth Profile for C₆₀ Bombardment of a Molecular solid

2013

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“…As these mono- or diatomic primary ions penetrate deep into the sample, causing extensive damage to the chemical bonds and the mixing of atomic/molecular layers, larger molecular as well as cluster primary ions were introduced, especially for molecular depth profiling. 19 , 38 − 41 The energy of the monatomic primary ions is focused on a small radius crater and deep in the subsurface layers, damaging and breaking molecules yet to be analyzed. 19 , 25 , 39 The energy of the polyatomic and cluster primary ions is distributed among all its constituent atoms and deposited mainly on the surface, resulting in less damage.…”

Section: Introductionmentioning

confidence: 99%

“… 19 , 25 , 39 The energy of the polyatomic and cluster primary ions is distributed among all its constituent atoms and deposited mainly on the surface, resulting in less damage. 39 − 41 Consequently, the most commonly applied energies for monatomic primary ions are in the range of a few 100 eV up to a few keV, 11 , 37 , 42 while for polyatomic ions they are in the range of a few keV up to a few 10 keV, mainly depending on their type. 19 , 22 , 25 , 40 The first widely applied polyatomic source was SF 5 + , closely followed by the fullerenes, C 60 + .…”

Section: Introductionmentioning

confidence: 99%

ToF-SIMS Depth Profiling of Metal, Metal Oxide, and Alloy Multilayers in Atmospheres of H₂, C₂H₂, CO, and O₂

Ekar

Panjan

Drev³

et al. 2021

J. Am. Soc. Mass Spectrom.

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The influence of the flooding gas during ToF-SIMS depth profiling was studied to reduce the matrix effect and improve the quality of the depth profiles. The profiles were measured on three multilayered samples prepared by PVD. They were composed of metal, metal oxide, and alloy layers. Dual-beam depth profiling was performed with 1 keV Cs + and 1 keV O 2 + sputter beams and analyzed with a Bi + primary beam. The novelty of this work was the application of H 2 , C 2 H 2 , CO, and O 2 atmospheres during SIMS depth profiling. Negative cluster secondary ions, formed from sputtered metals/metal oxides and the flooding gases, were analyzed. A systematic comparison and evaluation of the ToF-SIMS depth profiles were performed regarding the matrix effect, ionization probability, chemical sensitivity, sputtering rate, and depth resolution. We found that depth profiling in the C 2 H 2 , CO, and O 2 atmospheres has some advantages over UHV depth profiling, but it still lacks some of the information needed for an unambiguous determination of multilayered structures. The ToF-SIMS depth profiles were significantly improved during H 2 flooding in terms of matrix-effect reduction. The structures of all the samples were clearly resolved while measuring the intensity of the M n H m – , M n O m – , M n O m H – , and M n – cluster secondary ions. A further decrease in the matrix effect was obtained by normalization of the measured signals. The use of H 2 is proposed for the depth profiling of metal/metal oxide multilayers and alloys.

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“…Cluster secondary ion mass spectrometry (SIMS) has emerged as a unique tool for the two- and three-dimensional (2D/3D) characterization of complex organic materials, including biological cells. − The critical breakthrough for this technology is the discovery that by employing primary ion beams such as Bi 3 + , C 60 , or Ar n , with n = 500–5000, mass spectra can be acquired during erosion of the sample without undue chemical damage accumulation. , Moreover, since the beams are focusable to a submicron spot, high-resolution chemical imaging has become a major distinguishing feature of the technique. In concert with the development of these primary ion sources, there have also been rapid advances in instrumentation that seeks to maximize the properties associated with the desorption events.…”

Section: Introductionmentioning

confidence: 99%

Reducing the Matrix Effect in Molecular Secondary Ion Mass Spectrometry by Laser Post-Ionization

et al. 2017

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Strategies to reduce and overcome matrix effects in molecular secondary ion mass spectrometry (SIMS) are investigated using laser-based post-ionization of sputtered neutral organic molecules released under C 60 + bombardment. Using a twocomponent multilayer film similar to that employed in a recent VAMAS interlaboratory study, SIMS depth profiles of the protonated and deprotonated quasi-molecular ions of two well-studied organic molecules, Irganox 1010 and Irganox 1098, were measured along with that of the corresponding neutral precursor molecules. When compared to composition-dependent ionization probability changes of the secondary ions, the resulting profiles are much improved. We demonstrate that detection of neutral molecules via laser post-ionization yields significantly reduced matrix effects when compared to SIMS depth profiles in both positive and negative secondary ion mode. These results suggest that this approach may provide a useful pathway for acquiring depth profiles from complex organic samples with improved capabilities for quantitation.

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Molecular Depth Profiling with Cluster Ion Beams

Cited by 7 publications

References 168 publications

Computed Molecular Depth Profile for C₆₀ Bombardment of a Molecular solid

Computed Molecular Depth Profile for C₆₀ Bombardment of a Molecular solid

ToF-SIMS Depth Profiling of Metal, Metal Oxide, and Alloy Multilayers in Atmospheres of H₂, C₂H₂, CO, and O₂

Reducing the Matrix Effect in Molecular Secondary Ion Mass Spectrometry by Laser Post-Ionization

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Molecular Depth Profiling with Cluster Ion Beams

Cited by 7 publications

References 168 publications

Computed Molecular Depth Profile for C60 Bombardment of a Molecular solid

Computed Molecular Depth Profile for C60 Bombardment of a Molecular solid

ToF-SIMS Depth Profiling of Metal, Metal Oxide, and Alloy Multilayers in Atmospheres of H2, C2H2, CO, and O2

Reducing the Matrix Effect in Molecular Secondary Ion Mass Spectrometry by Laser Post-Ionization

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Computed Molecular Depth Profile for C₆₀ Bombardment of a Molecular solid

Computed Molecular Depth Profile for C₆₀ Bombardment of a Molecular solid

ToF-SIMS Depth Profiling of Metal, Metal Oxide, and Alloy Multilayers in Atmospheres of H₂, C₂H₂, CO, and O₂