1
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Galashev AE, Polukhin VA. Simulation of the removal of a lead film from graphene by the irradiation of a target with a beam of xenon clusters. RUSSIAN JOURNAL OF PHYSICAL CHEMISTRY B 2016. [DOI: 10.1134/s1990793116010164] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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2
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Kraft ML, Klitzing HA. Imaging lipids with secondary ion mass spectrometry. Biochim Biophys Acta Mol Cell Biol Lipids 2014; 1841:1108-19. [PMID: 24657337 DOI: 10.1016/j.bbalip.2014.03.003] [Citation(s) in RCA: 85] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2013] [Revised: 03/11/2014] [Accepted: 03/12/2014] [Indexed: 10/25/2022]
Abstract
This review discusses the application of time-of-flight secondary ion mass spectrometry (TOF-SIMS) and magnetic sector SIMS with high lateral resolution performed on a Cameca NanoSIMS 50(L) to imaging lipids. The similarities between the two SIMS approaches and the differences that impart them with complementary strengths are described, and various strategies for sample preparation and to optimize the quality of the SIMS data are presented. Recent reports that demonstrate the new insight into lipid biochemistry that can be acquired with SIMS are also highlighted. This article is part of a Special Issue entitled Tools to study lipid functions.
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Affiliation(s)
- Mary L Kraft
- Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA; Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
| | - Haley A Klitzing
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
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3
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Kennedy PE, Postawa Z, Garrison BJ. Dynamics Displayed by Energetic C60 Bombardment of Metal Overlayers on an Organic Substrate. Anal Chem 2013; 85:2348-55. [DOI: 10.1021/ac303348y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Paul E. Kennedy
- Department of Chemistry, 104
Chemistry Building, Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Zbigniew Postawa
- Smoluchowski Institute of Physics, Jagiellonian University, ul. Reymonta 4, 30-059 Kraków,
Poland
| | - Barbara J. Garrison
- Department of Chemistry, 104
Chemistry Building, Pennsylvania State University, University Park, Pennsylvania 16802, United States
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4
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Kennedy PE, Garrison BJ. Chemical damage resulting from 15 keV C60
, Ar18
and Ar60
cluster bombardments of solid benzene. SURF INTERFACE ANAL 2012. [DOI: 10.1002/sia.5022] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Paul E. Kennedy
- Department of Chemistry; The Pennsylvania State University; 104 Chemistry Building, University Park PA 16802 USA
| | - Barbara J. Garrison
- Department of Chemistry; The Pennsylvania State University; 104 Chemistry Building, University Park PA 16802 USA
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5
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Effect of sample rotation on surface roughness with keV C60 bombardment in secondary ion mass spectrometry (SIMS) experiments. Chem Phys Lett 2011. [DOI: 10.1016/j.cplett.2011.03.003] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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6
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Lu C, Wucher A, Winograd N. Molecular depth profiling of buried lipid bilayers using C(60)-secondary ion mass spectrometry. Anal Chem 2011; 83:351-8. [PMID: 21121691 PMCID: PMC3075603 DOI: 10.1021/ac102525v] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
An organic delta layer system made of alternating Langmuir-Blodgett multilayers of barium arachidate (AA) and barium dimyristoyl phosphatidate (DMPA) was constructed to elucidate the factors that control depth resolution in molecular depth profile experiments. More specifically, one or several bilayers of DMPA (4.4 nm) were embedded in relatively thick (51 to 105 nm) multilayer stacks of AA, resulting in a well-defined delta layer model system closely resembling a biological membrane. 3-D imaging time-of-flight secondary ion mass spectrometry (TOF-SIMS) depth profile analysis was performed on this system using a focused buckminsterfullerene (C(60)) cluster ion beam. The delta layer depth response function measured in these experiments exhibits similar features as those determined in inorganic depth profiling, namely an asymmetric shape with quasi-exponential leading and trailing edges and a central Gaussian peak. The effects of sample temperature, primary ion kinetic energy, and incident angle on the depth resolution were investigated. While the information depth of the acquired SIMS spectra was found to be temperature independent, the depth resolution was found to be significantly improved at low temperature. Ion induced mixing is proposed to be largely responsible for the broadening, rather than topography, as determined by atomic force microscopy (AFM); therefore, depth resolution can be optimized using lower kinetic energy, glancing angle, and liquid nitrogen temperature.
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Affiliation(s)
- Caiyan Lu
- Department of Chemistry, Pennsylvania State University, 104 Chemistry Building, University Park, Pennsylvania 16802 USA
| | - Andreas Wucher
- Faculty of Physics, University Duisburg-Essen, 47048 Duisburg, Germany
| | - Nicholas Winograd
- Department of Chemistry, Pennsylvania State University, 104 Chemistry Building, University Park, Pennsylvania 16802 USA
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7
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Ponomarev MG, Garrison BJ, Vickerman JC, Webb RP. A molecular dynamics study of a 5 keV C60 fullerene impact on a two-component organic molecular sample. SURF INTERFACE ANAL 2011. [DOI: 10.1002/sia.3527] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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8
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Philipp P, Yue Y, Wirtz T, Kieffer J. Ion-matter interactions by MD simulations making use of reactive force fields. SURF INTERFACE ANAL 2011. [DOI: 10.1002/sia.3427] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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9
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Abstract
This article reviews the new physics and new applications of secondary ion mass spectrometry using cluster ion probes. These probes, particularly C(60), exhibit enhanced molecular desorption with improved sensitivity owing to the unique nature of the energy-deposition process. In addition, these projectiles are capable of eroding molecular solids while retaining the molecular specificity of mass spectrometry. When the beams are microfocused to a spot on the sample, bioimaging experiments in two and three dimensions are feasible. We describe emerging theoretical models that allow the energy-deposition process to be understood on an atomic and molecular basis. Moreover, experiments on model systems are described that allow protocols for imaging on biological materials to be implemented. Finally, we present recent applications of imaging to biological tissue and single cells to illustrate the future directions of this methodology.
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Affiliation(s)
- Nicholas Winograd
- Department of Chemistry, Pennsylvania State University, University Park, Pennsylvania 16802, USA.
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10
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Delcorte A, Garrison BJ, Hamraoui K. Dynamics of Molecular Impacts on Soft Materials: From Fullerenes to Organic Nanodrops. Anal Chem 2009; 81:6676-86. [DOI: 10.1021/ac900746x] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- A. Delcorte
- Unité PCPM, Université Catholique de Louvain, 1 Croix du Sud, B-1348, Louvain-la-Neuve, Belgium, and Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802
| | - B. J. Garrison
- Unité PCPM, Université Catholique de Louvain, 1 Croix du Sud, B-1348, Louvain-la-Neuve, Belgium, and Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802
| | - K. Hamraoui
- Unité PCPM, Université Catholique de Louvain, 1 Croix du Sud, B-1348, Louvain-la-Neuve, Belgium, and Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802
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11
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Paruch R, Rzeznik L, Czerwinski B, Garrison BJ, Winograd N, Postawa Z. Molecular dynamics simulations of sputtering of Langmuir-Blodgett multilayers by keV C(60) projectiles. THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2009; 113:5641. [PMID: 20174461 PMCID: PMC2822397 DOI: 10.1021/jp809769q] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Coarse-grained molecular dynamics computer simulations are applied to investigate fundamental processes induced by an impact of keV C(60) projectile at an organic overlayer composed of long, well-organized linear molecules. The energy transfer pathways, sputtering yields, and the damage induced in the irradiated system, represented by a Langmuir-Blodgett (LB) multilayers composed from molecules of bariated arachidic acid, are investigated as a function of the kinetic energy and impact angle of the projectile and the thickness of the organic system. In particular, the unique challenges of depth profiling through a LB film vs. a more isotropic solid are discussed.The results indicate that the trajectories of projectile fragments and, consequently, the primary energy can be channeled by the geometrical structure of the overlayer. Although, a similar process is known from sputtering of single crystals by atomic projectiles, it has not been anticipated to occur during C(60) bombardment due to the large size of the projectile. An open and ordered molecular structure of LB films is responsible for such behavior. Both the extent of damage and the efficiency of sputtering depend on the kinetic energy, the impact angle, and the layer thickness. The results indicate that the best depth profiling conditions can be achieved with low-energy cluster projectiles irradiating the organic overlayer at large off-normal angles.
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Affiliation(s)
- R. Paruch
- Smoluchowski Institute of Physics, Jagiellonian University, ul. Reymonta 4, 30-059 Kraków, Poland
| | - L. Rzeznik
- Smoluchowski Institute of Physics, Jagiellonian University, ul. Reymonta 4, 30-059 Kraków, Poland
| | - B. Czerwinski
- Smoluchowski Institute of Physics, Jagiellonian University, ul. Reymonta 4, 30-059 Kraków, Poland
| | - B. J. Garrison
- Department of Chemistry, The Pennsylvania State University, University Park, PA 16802, USA
| | - N. Winograd
- Department of Chemistry, The Pennsylvania State University, University Park, PA 16802, USA
| | - Z. Postawa
- Smoluchowski Institute of Physics, Jagiellonian University, ul. Reymonta 4, 30-059 Kraków, Poland
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12
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Garrison BJ, Postawa Z, Ryan KE, Vickerman JC, Webb RP, Winograd N. Internal energy of molecules ejected due to energetic C60 bombardment. Anal Chem 2009; 81:2260-7. [PMID: 19228010 PMCID: PMC2666284 DOI: 10.1021/ac802399m] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
The early stages of C(60) bombardment of octane and octatetraene crystals are modeled using molecular dynamics simulations with incident energies of 5-20 keV. Using the AIREBO potential, which allows for chemical reactions in hydrocarbon molecules, we are able to investigate how the projectile energy is partitioned into changes in potential and kinetic energy as well as how much energy flows into reacted molecules and internal energy. Several animations have been included to illustrate the bombardment process. The results show that the material near the edge of the crater can be ejected with low internal energies and that ejected molecules maintain their internal energies in the plume, in contrast to a collisional cooling mechanism previously proposed. In addition, a single C(60) bombardment was able to create many free and reacted H atoms which may aid in the ionization of molecules upon subsequent bombardment events.
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Affiliation(s)
- Barbara J Garrison
- Department of Chemistry, 104 Chemistry Building, Pennsylvania State University, University Park, Pennsylvania 16802, USA.
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13
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Three-dimensional depth profiling of molecular structures. Anal Bioanal Chem 2009; 393:1835-42. [PMID: 19153718 DOI: 10.1007/s00216-008-2596-5] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2008] [Revised: 12/10/2008] [Accepted: 12/16/2008] [Indexed: 10/21/2022]
Abstract
Molecular time of flight secondary ion mass spectrometry (ToF-SIMS) imaging and cluster ion beam erosion are combined to perform a three-dimensional chemical analysis of molecular films. The resulting dataset allows a number of artifacts inherent in sputter depth profiling to be assessed. These artifacts arise from lateral inhomogeneities of either the erosion rate or the sample itself. Using a test structure based on a trehalose film deposited on Si, we demonstrate that the "local" depth resolution may approach values which are close to the physical limit introduced by the information depth of the (static) ToF-SIMS method itself.
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14
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Fletcher JS, Rabbani S, Henderson A, Blenkinsopp P, Thompson SP, Lockyer NP, Vickerman JC. A New Dynamic in Mass Spectral Imaging of Single Biological Cells. Anal Chem 2008; 80:9058-64. [DOI: 10.1021/ac8015278] [Citation(s) in RCA: 225] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- John S. Fletcher
- Manchester Interdisciplinary Biocentre, School of Chemical Engineering and Analytical Science, University of Manchester, Manchester, U.K., Ionoptika Ltd., Southampton. U.K., and Scientific Analysis Instruments, Manchester, U.K
| | - Sadia Rabbani
- Manchester Interdisciplinary Biocentre, School of Chemical Engineering and Analytical Science, University of Manchester, Manchester, U.K., Ionoptika Ltd., Southampton. U.K., and Scientific Analysis Instruments, Manchester, U.K
| | - Alex Henderson
- Manchester Interdisciplinary Biocentre, School of Chemical Engineering and Analytical Science, University of Manchester, Manchester, U.K., Ionoptika Ltd., Southampton. U.K., and Scientific Analysis Instruments, Manchester, U.K
| | - Paul Blenkinsopp
- Manchester Interdisciplinary Biocentre, School of Chemical Engineering and Analytical Science, University of Manchester, Manchester, U.K., Ionoptika Ltd., Southampton. U.K., and Scientific Analysis Instruments, Manchester, U.K
| | - Steve P. Thompson
- Manchester Interdisciplinary Biocentre, School of Chemical Engineering and Analytical Science, University of Manchester, Manchester, U.K., Ionoptika Ltd., Southampton. U.K., and Scientific Analysis Instruments, Manchester, U.K
| | - Nicholas P. Lockyer
- Manchester Interdisciplinary Biocentre, School of Chemical Engineering and Analytical Science, University of Manchester, Manchester, U.K., Ionoptika Ltd., Southampton. U.K., and Scientific Analysis Instruments, Manchester, U.K
| | - John C. Vickerman
- Manchester Interdisciplinary Biocentre, School of Chemical Engineering and Analytical Science, University of Manchester, Manchester, U.K., Ionoptika Ltd., Southampton. U.K., and Scientific Analysis Instruments, Manchester, U.K
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15
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Wucher A, Cheng J, Winograd N. Molecular Depth Profiling using a C(60) Cluster Beam: the Role of Impact Energy. THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2008; 112:16550-16555. [PMID: 19855815 PMCID: PMC2662745 DOI: 10.1021/jp8049763] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Molecular depth profiling of organic overlayers was performed using a mass selected C(60) ion beam in conjunction with time-of-flight (TOF-SIMS) mass spectrometry. The characteristics of sputter depth profiles acquired for a 300-nm Trehalose film on silicon were studied as a function of the kinetic impact energy of the projectile ions. The results are interpreted in terms of a simple model describing the balance between sputter erosion and ion induced chemical damage. It is shown that the efficiency of the projectile to clean up the fragmentation debris produced by its own impact represents a key parameter governing the success of molecular depth profile analysis.
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Affiliation(s)
- Andreas Wucher
- Fachbereich Physik, Universität Duisburg-Essen, 47048 Duisburg, Germany
| | - Juan Cheng
- Department of Chemistry, Pennsylvania State University, 104 Chemistry Building, University Park, Pennsylvania 16802
| | - Nicholas Winograd
- Department of Chemistry, Pennsylvania State University, 104 Chemistry Building, University Park, Pennsylvania 16802
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16
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Zheng L, Wucher A, Winograd N. Depth resolution during C60+ profiling of multilayer molecular films. Anal Chem 2008; 80:7363-71. [PMID: 18778034 PMCID: PMC2880170 DOI: 10.1021/ac801056f] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Time-of-flight secondary ion mass spectrometry is utilized to characterize the response of Langmuir-Blodgett (LB) multilayers under the bombardment by buckminsterfullerene primary ions. The LB multilayers are formed by barium arachidate and barium dimyristoyl phosphatidate on a Si substrate. The unique sputtering properties of the C60 ion beam result in successful molecular depth profiling of both the single component and multilayers of alternating chemical composition. At cryogenic (liquid nitrogen) temperatures, the high mass signals of both molecules remain stable under sputtering, while at room temperature, they gradually decrease with primary ion dose. The low temperature also leads to a higher average sputter yield of molecules. Depth resolution varies from 20 to 50 nm and can be reduced further by lowering the primary ion energy or by using glancing angles of incidence of the primary ion beam.
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Affiliation(s)
- Leiliang Zheng
- Department of Chemistry, The Pennsylvania State University, 104 Chemistry Building, University Park, Pennsylvania 16802
| | - Andreas Wucher
- Physics Department, University of Duisburg–Essen, Duisburg, 47048 Germany
| | - Nicholas Winograd
- Department of Chemistry, The Pennsylvania State University, 104 Chemistry Building, University Park, Pennsylvania 16802
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17
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Ryan KE, Garrison BJ. Cluster size dependence and yield linearity in cluster bombardment simulations of benzene. Anal Chem 2008; 80:6666-70. [PMID: 18686971 DOI: 10.1021/ac800995w] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Cluster bombardment of a molecular solid, benzene, is modeled using molecular dynamics simulations in order to investigate the effect of projectile cluster size and incident energy on the resulting yield. Using the mesoscale energy deposition footprint (MEDF) model, we are able to model large projectiles with incident energies from 5 to 140 keV and predict trends in ejection yield. The highest ejection yield at 5 keV was observed at C 20 and C 60, but shifts toward larger clusters for higher energies. These trends are explained in terms of the MEDF model. For these projectiles, all of the incident energy is deposited in the near-surface region, which is optimal for the projectile energy to contribute to the ejection yield. Because the energy is deposited in the optimal position for contributing to the ejection process, the yields increase linearly with incident energy with a slope that is nearly independent of the cluster size.
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Affiliation(s)
- Kathleen E Ryan
- Department of Chemistry, Pennsylvania State University, University Park, Pennsylvania 16802, USA
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18
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Garrison BJ, Postawa Z. Computational view of surface based organic mass spectrometry. MASS SPECTROMETRY REVIEWS 2008; 27:289-315. [PMID: 18421766 DOI: 10.1002/mas.20165] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Surface based mass spectrometric approaches fill an important niche in the mass analysis portfolio of tools. The particular niche depends on both the underlying physics and chemistry of molecule ejection as well as experimental characteristics. In this article, we use molecular dynamics computer simulations to elucidate the fundamental processes giving rise to ejection of organic molecules in atomic and cluster secondary ion mass spectrometry (SIMS), massive cluster impact (MCI) mass spectrometry, and matrix-assisted laser desorption ionization (MALDI) mass spectrometry. This review is aimed at graduate students and experimental researchers.
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Affiliation(s)
- Barbara J Garrison
- Department of Chemistry, Penn State University, 104 Chemistry Building, University Park, Pennsylvania 16802, USA.
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19
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Ryan KE, Garrison BJ. Energy deposition control during cluster bombardment: a molecular dynamics view. Anal Chem 2008; 80:5302-6. [PMID: 18522431 DOI: 10.1021/ac800287k] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Molecular dynamics simulations are performed to model C60 and Au3 bombardment of a molecular solid, benzene, in order to understand the energy deposition placement as a function of incident kinetic energy and incident angle. Full simulations are performed for 5 keV projectiles, and the yields are calculated. For higher energies, 20 and 40 keV, the mesoscale energy deposition footprint model is employed to predict trends in yield. The damage accumulation is discussed in relationship to the region where energy is deposited to the sample. The simulations show that the most favorable conditions for increasing the ejection yield and decreasing the damage accumulation are when most of the projectile energy is deposited in the near-surface region. For molecular organic solids, grazing angles are the best choice for achieving these conditions.
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Affiliation(s)
- Kathleen E Ryan
- Department of Chemistry, 104 Chemistry Building, Pennsylvania State University, University Park, Pennsylvania 16802, USA
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20
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De Mondt R, Van Vaeck L, Heile A, Arlinghaus HF, Nieuwjaer N, Delcorte A, Bertrand P, Lenaerts J, Vangaever F. Ion yield improvement for static secondary ion mass spectrometry by use of polyatomic primary ions. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2008; 22:1481-1496. [PMID: 18401858 DOI: 10.1002/rcm.3533] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Static secondary ion mass spectrometry (S-SIMS) is one of the potentially most powerful and versatile tools for the analysis of surface components at the monolayer level. Current improvements in detection limit (LOD) and molecular specificity rely on the optimisation of the desorption-ionisation (DI) process. As an alternative to monoatomic projectiles, polyatomic primary ion (P.I.) bombardment increases ion yields non-linearly. Common P.I. sources are Ga+ (liquid metal ion gun (LMIG), SF5+ (electron ionisation) and the newer Au(n)+, Bi(n)q+ (both LMIG) and C60+ (electron ionisation) sources. In this study the ion yield improvement obtained by using the newly developed ion sources is assessed. Two dyes (zwitterionic and/or thermolabile polar functionalities on a largely conjugated backbone) were analysed as a thin layer using Ga+, SF5+, C60+, Bi+, Bi3(2+) and Bi5(2+) projectiles under static conditions. The study aims at evaluating the improvement in LOD, useful and characteristic yield and molecular specificity. The corrected total ion count values for the different P.I. sources are compared for different instruments to obtain a rough estimate of the improvements. Furthermore, tentative ionisation and fragmentation schemes are provided to describe the generation of radical and adduct ions. Characteristic ion yields are discussed for the different P.I. sources. An overview of the general appearances of the mass spectra obtained with the different P.I. sources is given to stress the major improvement provided by polyatomic P.I.s in yielding information at higher m/z values.
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Affiliation(s)
- Roel De Mondt
- MiTAC, University of Antwerp, Department of Chemistry (CDE), Universiteitsplein 1, B-2610 Wilrijk, Belgium.
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21
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Biddulph GX, Piwowar AM, Fletcher JS, Lockyer NP, Vickerman JC. Properties of C84 and C24H12 molecular ion sources for routine TOF-SIMS analysis. Anal Chem 2007; 79:7259-66. [PMID: 17822312 DOI: 10.1021/ac071442x] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
C84+ and coronene (C24H12+) have been studied as primary ions for use in secondary ion mass spectrometry. A representative range of samples has been used to compare the effectiveness of each primary ion with the existing C60+, Au+, and Au3+ primary ions. It was found that C84 is the most effective primary ion providing higher secondary ion yields and a high molecular to fragment ion ratio. Coronene had a performance similar to C60. Coronene and C60 primary ions were also used to extend a previous study of matrix suppression/enhancement effects. The C60 was found to ameliorate this effect, possibly due to the increase in protonation in polyatomic sputtering, and coronene was found to further reduce suppression showing evidence of a chemical effect.
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Affiliation(s)
- Gregory X Biddulph
- Manchester Interdisciplinary Biocentre, University of Manchester, Manchester, M1 7DN, UK
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22
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Russo MF, Szakal C, Kozole J, Winograd N, Garrison BJ. Sputtering yields for C60 and Au3 bombardment of water ice as a function of incident kinetic energy. Anal Chem 2007; 79:4493-8. [PMID: 17503768 PMCID: PMC2553706 DOI: 10.1021/ac070105l] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
The total sputtering yields for water ice due to kiloelectronvolt cluster bombardment have been measured and compared to the predictions made by the mesoscale energy deposition footprint (MEDF) model. For C60 bombardment, the experimental yield varies almost linearly from 820 water molecule equivalents at an incident kinetic energy of 10 keV to 10 100 water molecule equivalents at a kinetic energy of 120 keV. For Au3 bombardment, the experimental yield varies almost linearly from 630 water molecule equivalents at an incident energy of 10 keV and rises to 1200 water molecule equivalents at 25 keV. The MEDF model is used to calculate relative yield trends with respect to incident energy using short-time molecular dynamics simulations. The results of these calculations indicate that the model can effectively predict the yield trends observed for these two clusters in experiments, although there is a consistent overestimate of the predicted induced C60 yield. It is hypothesized that this overestimate can be explained by the absence of reactions and ionization processes in the current simulations. Despite this omission, experimental yield trends can be accurately predicted using relatively small amounts of computer time. The success of the model in predicting the yield of water from ice films using a variety of energies and projectiles suggests this approach may greatly aid in the optimization of experimental configurations.
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Affiliation(s)
- Michael F Russo
- Department of Chemistry, Penn State University, 104 Chemistry Building, University Park, Pennsylvania 16802, USA
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