Extremely low-energy projectiles for SIMS using size-selected gas cluster ions

Moritani, Kousuke; Hashinokuchi, Michihiro; Nakagawa, Jun; Kashiwagi, Takahiro; Toyoda, Noriaki; Mochiji, Kōzō

doi:10.1016/j.apsusc.2008.05.010

Cited by 37 publications

(42 citation statements)

References 15 publications

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“…Details of the experimental setup have been previously reported [9,12]. Briefly, neutral Ar clusters were generated by supersonic expansion of Ar gas at a pressure of 0.5-1. ment from a tungsten filament, and the resulting cluster ions were then extracted at an acceleration voltage of 2∼10 kV.…”

Section: A Methodsmentioning

confidence: 99%

“…In contrast, small Ar cluster ions such as Ar + 2 or Ar + 3 are much more stable because of the high binding energies between the Ar ion and the Ar atom(s). We have developed instrumentation for producing Ar cluster ions containing 100-10,000 Ar atoms and for mass analysis of the dissociation of the cluster ions upon impact with a solid [9][10][11][12]. Importantly, this instrument lowers the average kinetic energy per Ar atom (E at ) of the cluster ion to less than the binding energy of solids ( < ∼ 5 eV), which leads to nondestructive cleaning or probing.…”

Section: Introductionmentioning

confidence: 99%

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Argon Cluster Ions Cleaning and Probing a Graphene Layer on Copper

Mochiji

Inui

Asa

et al. 2015

e-J. Surf. Sci. Nanotech.

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We demonstrate a method to clean and probe a graphene layer on copper by using cluster ions consisting of thousands of argon (Ar) atoms. Ar cluster ions colliding with a solid at kinetic energies below ∼5 eV/atom dissociate into smaller cluster ions such as Ar + 2 or Ar + 3 , and the dissociation rate (ease of dissociation) depends on the physical property of the solid. We apply this phenomenon to probe a graphene layer on copper. Contaminants at the graphene surface are removed without damage to the surface by Ar cluster ion bombardment and the cleanliness of the surface is simultaneously probed by measuring the dissociation rate. This rate gradually approaches the value for a clean surface. After cleaning, the dissociation rate for pristine graphene on copper is five times lower than that for bare copper, indicating that the graphene layer acts as a buffer against the impact force of the cluster ion upon collision. Accordingly, the method can probe the quality of graphene, such as carbon coverage, by comparing the dissociation rate with that for bare copper. Furthermore, the method can probe the interface between graphene and copper, showing that the dissociation rate increases with increasing copper oxidation. The obtained experimental results are compared with simulated results obtained by molecular dynamics simulation for the collisions of an Ar cluster ion with graphene on copper. The combined results are discussed with respect to the utility of the proposed method for controlling the quality of graphene in the manufacture of electronic or mechanical devices.

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Section: A Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Argon Cluster Ions Cleaning and Probing a Graphene Layer on Copper

Mochiji

Inui

Asa

et al. 2015

e-J. Surf. Sci. Nanotech.

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“…[12] As a result of using this equipment for various peptides and proteins, the peak intensity of fragment ions of the sample molecules was decreased by a factor of 10 2 when the kinetic energy per atom of the incident Ar-cluster ions was decreased below 5 eV, and intact ions of insulin (molecular weight: 5808) and cytochrome C (molecular weight: 12 327) could be detected without using any matrix. [13] Although there has been much progress in the use of Arcluster ions as projectiles for the detection of intact ions of bio-molecules, details of the role of the cluster ions, such as in soft-sputtering by Ar-cluster ions, remain unknown.…”

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confidence: 99%

Soft‐sputtering of insulin films in argon‐cluster secondary ion mass spectrometry

Oshima

Kashihara

Moritani

et al. 2011

Rapid Comm Mass Spectrometry

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In secondary ion mass spectrometry (SIMS) of organic substances, the dissociation of the sample molecules is crucial. We have developed SIMS equipment capable of bombardment, where the primary ions are argon cluster ions with kinetic energy per atom controllable down to 1 eV. We previously reported the detection of intact ions of insulin and cytochrome C using this equipment. In this paper, we present a detailed characterization of the emission of secondary ions from insulin, focusing on the difference in secondary ion yield between intact ions and fragment ions by varying the incident angle of the cluster ions. The emission intensity of the intact ions was changed drastically due to the exposed dosage and incident angle of the cluster ions in contrast to the fragment ions. We discuss these results based on the manner in which the argon-cluster ions collide with the organic solid.

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“…Among cluster ion beam technologies, gas cluster ion beam (GCIB) bombardment techniques [12] have been demonstrated to be very effective for low damage SIMS. Moritani and coworkers have developed SIMS instrumentation in which the cluster size of Ar cluster ions was selected to adjust the kinetic energy per atom of the cluster ion [13]. They investigated secondary ion mass spectra of polystyrene (PS) thin film using a size-selected Ar GCIB [14], and showed that the PS surface was bombarded with cluster ions involving 480 ∼ 4600 Ar atoms, and thus had a low kinetic energy per atom (E atom ) between 1.0 and 22 eV.…”

Section: Introductionmentioning

confidence: 99%

Fragment Distribution of Polystyrene by QMD Method Using the Model Hexamer

Hayashi

Moritani

Matsumoto

et al. 2010

JSA

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A quantum molecular dynamics (QMD) due to the force function of MO with the velocity Verlet algorithm using the polystyrene (PS) hexamer was performed to simulate secondary ion mass spectra (SIMS) of the polymer. We assumed that the QMD calculation corresponds to the thermal sputtering process in Sigmund proposal, and tried to analyze experimental mass spectra of PS with size-selected Ar gas cluster ion beam (GCIB) bombardments from the calculated mass spectra, because the Ar GCIB bombardments are considered as the sputtering by elastic collisions proposed by Sigmund. The calculated positive ion mass spectra for PS 6mer from the atomic charge analysis of the fragments at the 5000 MD (2.5 ps) step for total 60 trajectories of 0.77, 0.86 and 0.95 eV energy controls seem to be roughly in accordance with the experimental secondary positive ion results with the Ar + primary ion bombardments. From analysis of energy-dependency (0.43 ∼ 1.03 eV) for the PS model in QMD, the calculated relative intensities of fragments (C 2 H

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Extremely low-energy projectiles for SIMS using size-selected gas cluster ions

Cited by 37 publications

References 15 publications

Argon Cluster Ions Cleaning and Probing a Graphene Layer on Copper

Argon Cluster Ions Cleaning and Probing a Graphene Layer on Copper

Soft‐sputtering of insulin films in argon‐cluster secondary ion mass spectrometry

Fragment Distribution of Polystyrene by QMD Method Using the Model Hexamer

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