研究者詳細 - 青木学聡

論文 - 青木学聡

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Matrix-free high-resolution imaging mass spectrometry with high-energy ion projectiles 査読有り

Nakata, Y; Honda, Y; Ninomiya, S; Seki, T; Aoki, T; Matsuo, J

JOURNAL OF MASS SPECTROMETRY 44 巻 ( 1 ) 頁： 128 - 136 2009年1月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Journal of Mass Spectrometry

The importance of imaging mass spectrometry (MS) for visualizing the spatial distribution of molecular species in biological tissues and cells is growing. We have developed a new system for imaging MS using MeV ion beams, termed MeV-secondary ion mass spectrometry (MeV-SIMS) here, and demonstrated more than 1000-fold increase in molecular ion yield from a peptide sample (1154 Da), compared to keV ion irradiation. This significant enhancement of the molecular ion yield is attributed to electronic excitation induced in the near-surface region by the impact of high energy ions. In addition, the secondary ion efficiency for biologically important compounds (> 1 kDa) increased to more than 1010 cm-2, demonstrating that the current technique could, in principle, achieve micrometer lateral resolution. In addition to MeV-SIMS, peptide compounds were also analyzed with cluster-SIMS and the results indicated that in the former method the molecular ion yields increased substantially compared to the latter. To assess the capability of MeV-SIMS to acquire heavy-ion images, we have prepared a micropatterned peptide surface and successfully obtained mass spectrometric imaging of the deprotonated peptides (m/z 1153) without any matrix enhancement. The results obtained in this study indicate that the MeV-SIMS technique can be a powerful tool for high-resolution imaging in themass range from 100 to over 1000 Da. Copyright © 2008 John Wiley & Sons, Ltd.

DOI： 10.1002/jms.1482

A Processing Technique for Cell Surfaces Using Gas Cluster Ions for Imaging Mass Spectrometry 国際誌

Hideaki Yamada, Kazuya Ichiki, Yoshihiko Nakata, Satoshi Ninomiya, Toshio Seki, Takaaki Aoki, Jiro Matsuo

質量分析 57 巻 ( 3 ) 頁： 117 - 121 2009年

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：一般社団法人日本質量分析学会

We developed a processing technique for biological samples, that is, animal cells, for imaging mass spectrometry using gas cluster ion beams. Secondary ion mass spectrometry has been investigated for cellular imaging with high spatial resolution. Nanoscale processing techniques are needed for cellular level imaging, for example, for removing contamination from cell surfaces and exposing the insides of cells. In this study, we compared the mass spectrum of the unetched cell sample to that of the cell irradiated with an Ar cluster ion beam. The contamination was removed from the sample surface and the signals of intracellular components were detected. The results indicate that the cells were etched with low damage using the gas cluster ion beam. Finally, we compared the ion image of an unetched cell to that of an etched cell and demonstrated that the technique of cluster ion irradiation could be applied to the processing of samples for cellular level imaging mass spectrometry.

DOI： 10.5702/massspec.57.117

その他リンク： https://jlc.jst.go.jp/DN/JALC/00332526476?from=CiNii

Stress measurement of carbon cluster implanted layers with in-plane diffraction technique 査読有り

Matsuo J., Ichiki K., Hada M., Ninomiya S., Seki T., Aoki T., Nagayama T., Tanjyo M.

Extended Abstracts of the 9th International Workshop on Junction Technology, IWJT 2009 頁： 84 - 85 2009年

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）出版者・発行元：Extended Abstracts of the 9th International Workshop on Junction Technology, IWJT 2009

Cluster ion implantation has a great potential for semiconductor manufacturing, such as ultra shallow junction formation and strain engineering of channel. Stress in Si implanted with carbon cluster ions (C7H 7) was much higher than that in Si implanted with carbon monomer ions. Multiple collisions of atoms occurred during cluster ion implantation, and a fully amorphized Si layer can be formed. The stress in the implanted layer strongly depends on the annealing condition. There are two different directions for the stress. One is parallel to the surface, which is usually measured with conventional X-ray diffraction. The other is perpendicular to the surface, which can be measured with in-plane X-ray diffraction technique. The stress perpendicular to the surface was about 50% of the stress parallel to the surface even after flash lamp annealing. ©2009 IEEE.

DOI： 10.1109/IWJT.2009.5166225

A fragment-free ionization technique for organic mass spectrometry with large Ar cluster ions 査読有り

Ninomiya, S; Nakata, Y; Honda, Y; Ichiki, K; Seki, T; Aoki, T; Matsuo, J

APPLIED SURFACE SCIENCE 255 巻 ( 4 ) 頁： 1588 - 1590 2008年12月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Applied Surface Science

In this report, we propose to use the incidence of cluster ions that are much larger than molecular ions as a fragment-free ionization technique for organic secondary ion mass spectrometry. Secondary ions were measured for amino acid and peptide targets bombarded with 3, 8 and 13 keV large Ar cluster ions. The relative yields of the fragment ions decreased drastically with increasing incident cluster size. Fragment-free ionization of the molecule was accomplished when large cluster ions with optimized size and energy were incident on a biomolecular sample. © 2008 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.apsusc.2008.05.004

High-Speed Nano-Processing with Cluster Ion Beams 査読有り国際誌

Toshio Seki, Takaaki Aoki, Jiro Matsuo

Transactions of the MRS-J 33 巻 ( 4 ) 2008年12月

High sputtering yields of organic compounds by large gas cluster ions 査読有り

Ichiki, K; Ninomiya, S; Nakata, Y; Honda, Y; Seki, T; Aoki, T; Matsuo, J

APPLIED SURFACE SCIENCE 255 巻 ( 4 ) 頁： 1148 - 1150 2008年12月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Applied Surface Science

We measured the sputtering yield, surface roughness and surface damage of thin leucine films bombarded with Ar cluster ions and examined the usefulness of large gas cluster ions for the depth profiling of organic compounds. Ar cluster ion beams with a mean size of 2000 atoms/cluster and energies from 5 to 30 keV were used. Sputtering yields increased linearly with incident ion energy and were extremely high compared to inorganic materials. Surface damage was investigated by measuring positive secondary ions emitted from the leucine film before and after cluster ion irradiation. After irradiation the leucine surface became smoother. The yield ratio of protonated leucine ions to other fragment ions kept constant before and after Ar cluster ion irradiation. These results indicate that large gas cluster ions are useful for depth profiling of organic compounds. © 2008.

DOI： 10.1016/j.apsusc.2008.05.032

Low Damage Etching and SIMS Depth Profiling with Large Ar Cluster Ions 査読有り国際誌

Satoshi Ninomiya, Jiro Matsuo, Kazuya Ichiki, Hideaki Yamada, Yoshihiko Nakata, Yoshiro Honda, Toshio Seki, Takaaki Aoki

Transactions of the MRS-J 33 巻 ( 4 ) 2008年12月

SIMS Analysis of Biological Mixtures with Fast Heavy Ion Irradiation 査読有り国際誌

Yoshiro Honda, Yoshihiko Nakata, Satoshi Ninomiya, Toshio Seki, Takaaki Aoki, Jiro Matsuo

Transactions of the MRS-J 33 巻 ( 4 ) 2008年12月

Secondary ion emission from Si bombarded with large Ar cluster ions under UHV conditions 査読有り

Ninomiya, S; Ichiki, K; Nakata, Y; Honda, Y; Seki, T; Aoki, T; Matsuo, J

APPLIED SURFACE SCIENCE 255 巻 ( 4 ) 頁： 880 - 882 2008年12月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Applied Surface Science

Si was bombarded with size-selected 40 keV Ar cluster ions and positive secondary ions were measured using the time-of-flight technique under high and ultra-high vacuum (HV and UHV respectively) conditions. Si + ions were main species detected under the incidence of 40 keV Ar cluster ions, and the yields of Si cluster ions such as Si 4+ were also extremely high under both conditions. On the other hand, oxidized secondary ions such as SiO + were detected with high intensity only under the HV condition. The yield ratios of oxidized ions decreased in UHV to less than 1% of their values in HV. The effect of residual gas pressure on Si cluster ion yields is relatively low compared to oxidized ions, and the UHV condition is required to obtain accurate secondary ion yields. © 2008 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.apsusc.2008.05.063

MD simulation study of the sputtering process by high-energy gas cluster impact 査読有り

Aoki, T; Seki, T; Ninomiya, S; Matsuo, J

APPLIED SURFACE SCIENCE 255 巻 ( 4 ) 頁： 944 - 947 2008年12月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Applied Surface Science

We performed molecular dynamics (MD) simulations to study the characteristic sputtering process with large cluster ion impact. The statistical properties of incident Ar and sputtered Si atoms were examined using 100 different MD simulations with Ar 1000 cluster impacting on a Si(0 0 1) target at a total acceleration energy of 50 keV. The results show that the kinetic energy distribution of Ar atoms after impact obeys the high-temperature Boltzmann distribution due to thermalization through high-density multiple collisions on the target. On the other hand, the kinetic energy distribution of sputtered target atoms demonstrates a hybrid model of thermalization and collision-cascade desorption processes. © 2008 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.apsusc.2008.05.008

What size of cluster is most appropriate for SIMS? 査読有り

Matsuo, J; Ninomiya, S; Nakata, Y; Honda, Y; Ichiki, K; Seki, T; Aoki, T

APPLIED SURFACE SCIENCE 255 巻 ( 4 ) 頁： 1235 - 1238 2008年12月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Applied Surface Science

Secondary ion emission with large gas cluster ion is reviewed from the point of view of secondary ion mass spectroscopy (SIMS). We have proposed to use large cluster ions to realize fragment-free ionization for SIMS analysis for various organic materials, such as amino acids and peptides. When large cluster ions with optimized size and energy were incident on biomolecular samples, the relative yields of the fragment ions decreased drastically with the velocity of incident cluster ions. Molecular depth profiling capability is also demonstrated by using large gas cluster ions as the primary ion for SIMS. © 2008 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.apsusc.2008.05.057

Yield enhancement of molecular ions with MeV ion-induced electronic excitation 査読有り

Nakata, Y; Honda, Y; Ninomiya, S; Seki, T; Aoki, T; Matsuo, J

APPLIED SURFACE SCIENCE 255 巻 ( 4 ) 頁： 1591 - 1594 2008年12月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Applied Surface Science

We performed secondary ion mass spectrometry for arginine thin films in the incident energy range from 10 keV to 2 MeV, in which electronic energy loss in the surface region increases with energy and exceeds the nuclear energy loss. The yield of protonated arginine increased with incident energy, and at 2 MeV it was approximately two orders of magnitude larger than at 10 keV, where the nuclear collision process is dominant. It was found that the molecular ion desorption is enhanced by the electronic excitation induced in the near-surface region. In addition, the yield ratios of the fragment ions to the protonated arginine decreased with incident energy, which indicates that the nuclear energy deposition significantly affects molecular fragmentation. These results demonstrate a soft desorption and ionization of biomolecules by the MeV ion-induced electronic excitation. © 2008 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.apsusc.2008.05.108

Carbon nanotubes from a divided catalyst: the carbon transmission method 査読有り

Hikata Takeshi, Hayashi Kazuhiko, Mizukoshi Tomoyuki, Sakurai Yoshiaki, Ishigami Itsuo, Aoki Takaaki, Seki Toshio, Matsuo Jiro

APPLIED PHYSICS EXPRESS 1 巻 ( 3 ) 頁： 0340021 - 0340023 2008年3月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Applied Physics Express

We have fabricated carbon nanotubes (CNTs) using a catalyzed growth technique that we call the carbon transmission method (CTM). We could control independently functions for carbon source gas supply and CNT growth by using a foil barrier (Ag) penetrated by pure Fe fibers. CNTs grew on one end of the Fe fibers, formed from diffused carbon that originates in carbon source gas at the other end of the fibers. Long CNTs with length over 100 μm were obtained on the end of the Fe fibers In the carbon transmitted side. © 2008 The Japan Society of Applied Physics.

DOI： 10.1143/APEX.1.034002

Low damage smoothing of magnetic materials using off-nonnal gas cluster ion beam irradiation 査読有り

Kakuta, S; Sasaki, S; Furusawa, K; Seki, T; Aoki, T; Matsuo, J

SURFACE & COATINGS TECHNOLOGY 201 巻 ( 19-20 ) 頁： 8632 - 8636 2007年8月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Surface and Coatings Technology

A damage-free smoothing process for magnetic materials using a gas cluster ion beam (GCIB) has been studied. As the areal density of hard disk drives (HDDs) has increased, the flying height of the magnetic recording head above the disk has been decreasing. In order to further reduce the flying height and improve the sensitivity of sensors, a damage-free smoothing technology for magnetic materials is imperative. A GCIB process has been proposed as a novel smoothing technique for various materials. With this process it is expected that the damage will be low, since the gas clusters are aggregations of a few to thousands of atoms or molecules. In this paper, oblique GCIB irradiation has been studied in order to achieve low damage smoothing of PtMn and NiFe thin films. The surface morphology after GCIB irradiation was observed by scanning electron microscopy (SEM) and atomic force microscopy (AFM). A smooth surface with an average roughness of less than 1 nm was obtained by using oblique GCIB irradiation. Irradiation damage, such as fluctuations in the ratio of the material components and oxidation of the surface, were investigated by secondary ion mass spectrometry (SIMS). The fluctuations were suppressed by using oblique GCIB irradiation with incident angles larger than 80°. Consequently, irradiation from a GCIB at grazing incidence can be applied to achieve low-damage smoothing of magnetic materials. © 2007 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.surfcoat.2006.03.064

Molecular dynamics study of monomer and dimer emission processes with high energy gas cluster ion impact 査読有り

Aoki, T; Seki, T; Ninomiya, S; Matsuo, J

SURFACE & COATINGS TECHNOLOGY 201 巻 ( 19-20 ) 頁： 8427 - 8430 2007年8月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Surface and Coatings Technology

The mechanism of the sputtering process by energetic large cluster ion impacts was studied using molecular dynamics (MD) simulations. MD simulations of Ar1000 clusters accelerated with 50 keV total energy impacting on a Si(100) target were performed with 50 trials at different impact points in order to improve the statistical reliance. From these MD simulations, a sputtering yield of about 20 Si atoms/impact was obtained. Si clusters such as Si2, Si3, etc. were also found in the sputtered particles, and the sputtering yields for each cluster size obey the power-decay rule with a decay index of 2.3-3. The investigation of trajectories of sputtered Si1 and Si2 showed that initial coordinates of sputtered particles residing within a region corresponds to a crater-shaped hole caused by cluster impact. As for the sputtering of dimers, it is found that, not only the emission of a preformed dimer (i.e. a pair of target atoms initially bound before the cluster impact), but the emission of dynamically formed dimers through multiple collisions is also probable event for cluster impact. © 2007 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.surfcoat.2006.09.325

Molecular dynamics study of glancing angle gas cluster irradiation on irregular-structured surfaces 査読有り

Aoki, T; Matsuo, J

NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS 261 巻 ( 1-2 ) 頁： 639 - 642 2007年8月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms

Surface modification processes resulting from glancing angle gas cluster ion irradiation were studied by molecular dynamics (MD) simulations. Large Ar2000 gas clusters accelerated with 20 keV were irradiated onto Si(1 0 0) substrates to which were attached small Si block-shaped (size of 4096, 16384 or 65536 atoms) structures. The MD simulations revealed that when an Ar cluster is irradiated at 80° of incident angle, the cluster slides on the substrate surface without damage and impacts on the wall of the block structures causing multiple collisions, and dynamic deformation of the blocks. Especially, in the case of the impact on the small surface block (Si4096), a large part of the block was sputtered as a large chunk, and the target substrate was smoothed with only one cluster impact. The evaluation of the damage distribution showed that silicon interstitials, caused by the multiple collision mechanism, reside within 15Å from the surface, which suggests that low-damage and high-performance surface modification processing would be realized by utilizing a glancing angle gas cluster ion beam irradiation technique. © 2007 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.nimb.2007.04.005

Molecular dynamics simulations of surface smoothing and sputtering process with glancing-angle gas cluster ion beams 査読有り

Aoki, T; Matsuo, J

NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS 257 巻 ( 1-2 SPEC. ISS. ) 頁： 645 - 648 2007年4月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms

Surface modification processes with glancing-angle large gas cluster irradiation were studied by molecular dynamics simulations. The MD simulation of an Ar2000 gas cluster impacting on Si(1 0 0) substrate with small Si4096 block structure attached on the surface was performed. The MD result has shown that, when the Ar cluster impacts on the target at 20 keV of total acceleration energy and at 80° of incident angle, the incident cluster slides on the target surface without creating surface damage and most of the constituent atoms in the cluster collide with the sidewall of the surface block. Up to 10 keV of kinetic energy of the incident cluster was transferred to the target irregular structure, which results in the sputtering or stretching of the surface block and the target surface is smoothed. This characteristic surface modification effect was observed when the surface block is located farther than 200 Å from the point where the incident cluster contacts with the target surface. © 2007 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.nimb.2007.01.048

Size effect in cluster collision on solid surfaces 査読有り

Matsuo, J; Ninomiya, S; Nakata, Y; Ichiki, K; Aoki, T; Seki, T

NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS 257 巻 ( 1-2 SPEC. ISS. ) 頁： 627 - 631 2007年4月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms

New surface modification processes have been demonstrated using gas cluster ion irradiations. Multiple collision and high energy density collision of cluster ions are responsible for "non-linear phenomena", which play an important role in the surface modification process. Because of the unique interaction between cluster ions and surface atoms, atomistic mechanisms of cluster ion bombardment must be understood for the further developments of this technology. Cluster size is a unique parameter for cluster ions. One of the fundamental questions in this surface modification technique is the cluster size effect. It is important to use appropriate cluster size in each process. Size dependence of sputtering yields and secondary ion yields with large Ar cluster (N > 300) have been measured. © 2007 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.nimb.2007.01.164

Measurements of secondary ions emitted from organic compounds bombarded with large gas cluster ions 査読有り

Ninomiya, S; Nakata, Y; Ichiki, K; Seki, T; Aoki, T; Matsuo, J

NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS 256 巻 ( 1 ) 頁： 493 - 496 2007年3月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms

We propose to use cluster ions that are much larger than the molecular ions as primary ions for organic secondary ion mass spectrometry. Incident Ar cluster ion beams with energies from 10 to 20 keV and a mean size of about 1000 atoms/cluster were used. Secondary ions were measured for a thin arginine film target (200 nm) bombarded with large Ar cluster ions using a time-of-flight technique. Molecular ions of arginine and characteristic fragment ions were detected with high sensitivity. When large Ar cluster ions such as Ar1500 were incident on the arginine target, molecular ions of arginine were detected with little fragment ions. This indicates that large cluster ions can ionize arginine molecules without damaging them. © 2006 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.nimb.2006.12.047

The effect of incident cluster ion energy and size on secondary ion yields emitted from Si 査読有り

Ninomiya, S; Ichiki, K; Nakata, Y; Seki, T; Aoki, T; Matsuo, J

NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS 256 巻 ( 1 ) 頁： 528 - 531 2007年3月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms

Secondary ions produced from a Si target bombarded with Ar cluster ions much larger than the molecular ions have been investigated. Secondary ions have been measured for a Si target bombarded with large Ar cluster ions at an incident energy between 7.5 and 27.5 keV using a time-of-flight technique. The mean size of the Ar cluster ion was about 1000 atoms/cluster, and then the collision energy per atom is between a few tens of eV and a few hundreds of eV. Secondary silicon cluster ions were detected under large Ar cluster ion bombardment. In this study, we succeeded to accurately measure the dependence of secondary ion spectra obtained by large Ar cluster ions on the incident cluster-ion size using a time-of-flight technique combined a primary-ion beam deflector and a secondary-ion deflector. The dependence of the secondary ion spectra under large Ar cluster ion bombardment on the incident cluster size is discussed. © 2006 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.nimb.2006.12.074

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