青柳 里果

<title>Abstract</title>The dynamics of hydrogen in metals with mixed grain structure is not well understood at a microscopic scale. One of the biggest issues facing the hydrogen economy is “hydrogen embrittlement” of metal induced by hydrogen entering and diffusing into the material. Hydrogen diffusion in metallic materials is difficult to grasp owing to the non-uniform compositions and structures of metal. Here a time-resolved “operando hydrogen microscope” was used to interpret local diffusion behaviour of hydrogen in the microstructure of a stainless steel with austenite and martensite structures. The martensite/austenite ratios differed in each local region of the sample. The path of hydrogen permeation was inferred from the time evolution of hydrogen permeation in several regions. We proposed a model of hydrogen diffusion in a dual-structure material and verified the validity of the model by simulations that took into account the transfer of hydrogen at the interfaces.

We have improved an electron stimulated desorption (ESD) apparatus to obtain the time evolution of hydrogen permeation for cold-worked stainless steel. Hydrogen permeation through grain structures was visualized by using the operando hydrogen microscope combining ESD and hydrogen supply system. The diffusion coefficients in grains were calculated from time evolution curves of hydrogen permeation. Principal component analysis (PCA) of hydrogen maps was used to classify crystal grains by the degrees of hydrogen diffusion and permeation flux. Grain structures such as the ratio of austenite/martensite, crystallographic orientations and coherent/random grain boundaries were determined by electron backscatter diffraction (EBSD) analysis. The areas with high-speed and high flux permeation of hydrogen were characterized as smaller austenitic grains with grain boundaries. The usefulness of a combined ESD-PCA-EBSD analysis on hydrogen permeation in materials was demonstrated in the present study.

The protist (mostly single-celled organisms), Paramecium bursaria, forms an intracellular symbiotic relationship with the single-celled algae, Chlorella variabilis, where P. bursaria provides nutrients (i.e., Ca2+, Mg2+, and K+), carbon dioxide for photosynthesis and protection from viruses, while C. variabilis provides oxygen, carbon fixation, and nutrients. Key to this successful relationship is the perialgal vacuole (PV) membrane, which surrounds C. variabilis and protects it from digestion by P. bursaria. The membrane is fragile and difficult to analyze using conventional methods therefore very little is known about the molecular composition. We used the OrbiSIMS, a new high-resolution mass spectrometer with subcellular resolution imaging, to study the compartmentalization of endosymbionts and elucidate biomolecular interactions between the host and endosymbiont. Ions from the region of interest, close to C. variabilis, and specific to the target samples containing PVs were found based on the chemical mapping and masses of the ions. We show chemical localizations of oligosaccharides in close proximity of C. variabilis endosymbionts in P. bursaria. These oligosaccharides are detected in host-endosymbiont samples containing PV membrane-bound algae and absent in free-living algae and digestive vacuole (DV) membrane-bound algae in P. bursaria.

Time-of-flight secondary ion mass spectrometry (TOF-SIMS) is one of the most powerful methods to analyze biomolecules in biological tissues and cells because it provides detailed chemical structure information and chemical images with a high spatial resolution. However, in terms of quantitative analysis, there are issues such as matrix effects that often cause secondary ion intensity changes regardless of the actual concentration in a sample. For instance, the intensity of secondary ions related to peptides is generally suppressed when lipids coexist. Since the evaluation of biomolecules is crucial to understand biological phenomena, it is required to analyze peptides or lipids without matrix effects. Therefore, the mechanism of matrix effects regarding peptides and lipids in TOF-SIMS was investigated in this study. Leu-enkephalin (YGGFL, molecular weight of 555.3 Da) and 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC, C44H84NO8P, molecular weight 785.6 Da) were employed to prepare model samples. Model samples contain different weight ratios of these two molecules. The intensity of secondary ions related to the peptide or the lipid was compared with control samples containing pure leu-enkephalin or DOPC. As a result, it is indicated that the intensity of DOPC related secondary ions is strongly enhanced by coexisting leu-enkephalin, while the intensity of leu-enkephalin related secondary ions is suppressed by coexisting DOPC especially in a low concentration range of the peptide.

Mixed peptide/lipid samples were analyzed with respect to their chemical composition by means of desorption/ionization induced by neutral SO2 clusters (DINeC) in combination with mass spectrometry (MS). Depth profiles of the mixed films indicated a segregation layer of lipid on top of all samples. The thickness of this layer as obtained by DINeC-MS was in the order of one nanometer what can be seen as an upper limit for the depth resolution of DINeC-MS. The relative amounts of the substance of peptide and lipid derived for the bulk material of mixed samples with different compositions were found to be close to the nominal values indicating a low matrix effect. Throughout the depth profiles, only intact molecular ions [M+H]+ as well as dimers of peptides and lipids were detectable, indicating the soft nature of DINeC even when used for depth profiling of biomolecular samples.

Time-of-flight secondary ion mass spectrometry (TOF-SIMS) provides chemical images with a high spatial resolution, approximately 100 nm, and detailed chemical information. It is, however, often necessary to obtain images of higher spatial resolution and to detect high mass secondary ions with greater sensitivity, higher than several 100 Da. In this study, in order to improve the TOF-SIMS spatial resolution, image fusion using an image with a higher spatial resolution was evaluated based on principal component analysis (PCA). Moreover, in order to effectively detect important secondary ions with lower intensity, the intensity of one pixel was enhanced by integrating neighboring several pixels. According to the pixel reduction, the rank of the TOF-SIMS data matrix should be reduced. Due to the sparsity of TOF-SIMS data, sparse modeling techniques such as robust PCA were employed to the decomposition of the original data. In terms of image data fusion, PCA score distribution images of the model samples indicate the improvement of the spatial resolution without significant changes in PCA loadings after data fusion of TOF-SIMS and microscopy images. Regarding the improvement of low intensity secondary ion detection, PCA results before and after pixel reduction suggested that the pixel reduction was useful in detecting important low intensity secondary ions effectively.

Blood adsorption onto the inside surface of hollow fiber dialysis membranes was investigated by means of time-of-flight secondary ion mass spectrometry (TOF-SIMS) and near-field infrared microscopy (NFIR) in order to evaluate the biocompatibility and permeability of dialysis membranes. TOF-SIMS is useful for the imaging of particular molecules with a high spatial resolution of approximately 100 nm. In contrast, infrared spectra provide quantitative information and NFIR enables analysis with a high spatial resolution of less than 1 mu m, which is close to the resolution of TOF-SIMS. A comparison was made of one of the most widely used dialysis membranes made of polysulfone (PSf), that has an asymmetric and inhomogeneous pore structure, and a newly developed asymmetric cellulose triacetate (ATA) membrane that also has an asymmetric pore structure, even though the conventional cellulose triacetate membrane has a symmetric and homogeneous pore structure. As a result, it was demonstrated that blood adsorption on the inside surface of the ATA membrane is more reduced than that on the PSf membrane.

Matrix effects are crucial for analyses using time-of-flight secondary ion mass spectrometry (ToF-SIMS) in terms of quantitative analysis, depth profiling and imaging. It is often difficult to predict how co-existing materials will influence each other before such analysis. However, matrix effects need to be curtailed in order to assume the appropriate amount of a target material in a sample. First, matrix effects on different types of organic mixed samples, including a sample composed of Irganox 1010 and Irganox 1098 (MMK sample) and another composed of Irganox 1010 and Fmoc-pentafluoro-L-phenylalanine (MMF sample), were observed utilizing ToF-SIMS and the dependence of the secondary ion polarity of the matrix effects on the same sample was evaluated. Next, the correction method for the ToF-SIMS matrix effects proposed by Shard et al. was applied to a comparison of the positive secondary ion results to the negative ones. The matrix effects on the positive ion data in both samples were different from those on the negative ion data. The matrix effect correction method worked effectively on both the negative and positive depth profiles. Copyright (C) 2017 John Wiley & Sons, Ltd.

The applicability of internal additives for mass scale calibration in time-of-flight secondary ion mass spectrometry (TOF-SIMS) was studied. Relation between the ions selected for mass scale calibration and the relative mass accuracy of the target molecular ions was investigated. Didecyldimethylammonium bromide (dC10DMA(+)Br(-)), dioctadecyldimethylammonium chloride (dC18DMA(+)Cl(-)) and tetradecyltrimethylammonium chloride (C14TMA(+)Cl(-)) as target molecules and octadecyltrimethylammonium chloride (C18TMA(+)Cl(-)) as an internal additive were prepared for positive TOF-SIMS spectra. Tinuvin 770 as a target molecule and sodium hexadecyl sulfate (C16OSO3(-)Na(+)) as an internal additive were used to evaluate negative TOF-SIMS spectra. In the case of dC10DMA(+)Br(-), dC18DMA(+)Cl(-) and Tinuvin 770, the relative mass accuracy of the target molecular ions tends to be improved by mass scale calibration using the molecular ion of the internal additive. The relative mass accuracy of the molecular ion of the target ensured by the mass scale calibration using internal additives was less than approximately +/- 46ppm. In some cases, however, internal additives highly effect on samples and change the sample properties because of coverage of the sample, removing a target molecule or causing matrix effects. It is necessary to evaluate the influence of the internal additive addition before applying internal additives. The detection of target ion peak should be especially confirmed after the addition of the internal additive. When samples are not influenced by internal additive addition, the internal additive method is effective for accurate mass calibration. Copyright (c) 2016 John Wiley & Sons, Ltd.

The damage of polymer surfaces caused by the high energy primary ion beams of TOF-SIMS was examined using Ar cluster ions. Polymer damage, the damage of secondary ions detected from the polystyrene surface and the damage layer formed by the Bi-3 primary ion beam have previously been studied. In this study, the damage observed in the secondary ions was studied by using Ar cluster primary ions. The secondary ions were mainly classified into two types, ions reflecting the polystyrene structure and cyclized ions, generated by excessive energy, which are not useful for qualitative analysis. The layer damaged by irradiation of the Bi-3 primary ion regarding PS samples was confirmed using Ar cluster sputtering beams. The depth of the layer that has chemical damage in the PS main chain caused by 30kV Bi-3(++) (ion dose: 5x10(12)ions/cm(2)) irradiation was approximately 50-60nm. The Ar cluster ion sputter rate in PS decreases with the Bi-3 ion irradiation. Micro PS particles that are not able to be detected by a conventional TOF-SIMS measurement can be effectively analyzed by accumulating the secondary ions over the static limit using Ar cluster sputtering. Copyright (c) 2016 John Wiley & Sons, Ltd.

Amyloid beta (A) adsorption onto lipid membranes depending on the condition of a lipid was investigated by means of time-of-flight secondary ion mass spectrometry (ToF-SIMS). A aggregation depending on the different hardness of lipid membrane has not been clarified yet although it is important to understand Alzheimer's disease. A (1-40) on three different lipid membranes having different transition temperatures has been evaluated using ToF-SIMS in the previous study, and in this study, the differences between A on liquid crystalline-phase lipid membranes and that on gel-phase lipid membranes were investigated in order to clarify the mechanisms of aggregation and peptide folding change. ToF-SIMS secondary ion images clearly showed A distribution on lipid membranes. Because ToF-SIMS data is extremely complicated although it contains rich information, it was analysed by principal component analysis (PCA). Score images indicated by PCA are consistent with the images of secondary ions related to A and are clearer than the secondary ion images. Moreover, PCA results suggest the difference between A on different lipid membranes in terms of amino acid fragment ions, and the orientation of A on 1,2-dipalmitoyl-sn-glycero-3-phosphocholine was indicated. Copyright (c) 2016 John Wiley & Sons, Ltd.

Time-of-flight secondary ion mass spectrometry (ToF-SIMS) provides detailed chemical structure information and high spatial resolution images. Therefore, ToF-SIMS is useful for studying biological phenomena such as ischemia. In this study, in order to evaluate cerebral microinfarction, the distribution of biomolecules generated by ischemia was measured with ToF-SIMS. ToF-SIMS data sets were analyzed by means of multivariate analysis for interpreting complex samples containing unknown information and to obtain biomolecular mapping indicated by fragment ions from the target biomolecules. Using conventional ToF-SIMS (primary ion source: Bi cluster ion), it is difficult to detect secondary ions beyond approximately 1000 u. Moreover, the intensity of secondary ions related to biomolecules is not always high enough for imaging because of low concentration even if the masses are lower than 1000 u. However, for the observation of biomolecular distributions in tissues, it is important to detect low amounts of biological molecules from a particular area of tissue. Rat brain tissue samples were measured with ToF-SIMS (J105, Ionoptika, Ltd., Chandlers Ford, UK), using a continuous beam of Ar clusters as a primary ion source. ToF-SIMS with Ar clusters efficiently detects secondary ions related to biomolecules and larger molecules. Molecules detected by ToF-SIMS were examined by analyzing ToF-SIMS data using multivariate analysis. Microspheres (45 lm diameter) were injected into the rat unilateral internal carotid artery (MS rat) to cause cerebral microinfarction. The rat brain was sliced and then measured with ToF-SIMS. The brain samples of a normal rat and the MS rat were examined to find specific secondary ions related to important biomolecules, and then the difference between them was investigated. Finally, specific secondary ions were found around vessels incorporating microspheres in the MS rat. The results suggest that important biomolecules related to cerebral microinfarction can be detected by ToF-SIMS. (C) 2016 American Vacuum Society.

Amyloid beta (A beta) peptides are considered to be strongly related to Alzheimer's disease. A beta peptides form a beta-sheet structure on hard lipid membranes and it would aggregate to form amyloid fibrils, which are toxic to cells. However, the aggregation mechanism of A beta is not fully understood. To evaluate the influence of the lipid membrane condition for A beta aggregation, the adsorption forms of A beta (1-40) on mixture membranes of lipid 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) and cholesterol beta-D-glucoside (beta-CG) were investigated by time-of-flight secondary ion mass spectrometry. As a result, A beta adsorbed along the localized DMPC lipid on the mixture lipid membranes, whereas it was adsorbed homogeneously on the pure DMPC and beta-CG membranes. Moreover, amino acid fragments that mainly existed in the n-terminal of A beta (1-40) peptide were strongly detected on the localized DMPC region. These results suggested that the A beta was adsorbed along the localized DMPC lipid with a characteristic orientation. These findings suggest that the hardness of the membrane is very sensitive to coexisting materials and that surface hardness is important for aggregation of A beta. (C) 2016 American Vacuum Society.

A hair cuticle, which consists of flat overlapping scales that surround the hair fiber, protects inner tissues against external stimuli. The outermost surface of the cuticle is covered with a thin membrane containing proteins and lipids called the epicuticle. In a previous study, the authors conducted a depth profile analysis of a hair cuticle's amino acid composition to characterize its multilayer structure. Time-of-flight secondary ion mass spectrometry with a bismuth primary ion source was used in combination with the C-60 sputtering technique for the analysis. It was confirmed that the lipids and cysteine-rich layer exist on the outermost cuticle surface, which is considered to be the epicuticle, though the detailed structure of the epicuticle has not been clarified. In this study, depth profile analysis of the cuticle surface was conducted using the argon gas cluster ion beam (Ar-GCIB) sputtering technique, in order to characterize the structure of the epicuticle. The shallow depth profile of the cuticle surface was investigated using an Ar-GCIB impact energy of 5 keV. Compared to the other amino acid peaks rich in the epicuticle, the decay of 18-methyleicosanic acid (18-MEA) thiolate peak was the fastest. This result suggests that the outermost surface of the hair is rich in 18-MEA. In conclusion, our results indicate that the outermost surfaces of cuticles have a multilayer (lipid and protein layers), which is consistent with the previously proposed structure. (C) 2016 American Vacuum Society.

Peptide or protein structural analysis is crucial for the evaluation of biochips and biodevices, therefore an analytical technique with the ability to detect and identify protein and peptide species directly from surfaces with high lateral resolution is required. In this report, the efficacy of ToF-SIMS to analyze and identify proteins directly from surfaces is evaluated. Although the physics governing the SIMS bombardment process precludes the ability for researchers to detect intact protein or larger peptides of greater than a few thousand mass unit directly, it is possible to obtain information on the partial structures of peptides or proteins using low energy per atom argon duster ion beams. Large cluster ion beams, such as Ar dusters and C-60 ion beams, produce spectra similar to those generated by tandem MS. The SIMS bombardment process also produces peptide fragment ions not detected by conventional MS/MS techniques. In order to clarify appropriate measurement conditions for peptide structural analysis, peptide fragmentation dependency on the energy of a primary ion beam and ToF-SIMS specific fragment ions are evaluated. It was found that the energy range approximately 6 &lt;= E/n &lt;= 10 eV/atom is most effective for peptide analysis based on peptide fragments and [M + H] ions. We also observed the cleaving of side chain moieties at extremely low-energy E/n &lt;= 4 eV/atom.

飛行時間型二次イオン質量分析法(TOF-SIMS)は、製品表面の極薄および極小の有機物欠点の同定ツールとして期待されている。しかしながら、質量軸の精度が低いため、ピークの帰属は難しく、未知成分同定は困難である。そこで、内部添加剤を用いた質量軸較正法を考案した。モデル試料を用いた検証の結果、内部添加剤由来の高質量ピークを質量軸較正に用いることによる質量軸の精度の向上が確認された。

異なる化学情報が得られる分子分布計測手法である飛行時間型二次イオン質量分析（ToF-SIMS）と近接場赤外顕微鏡（NFIR）を用いて、同一試料化学分布を測定することにより、未知分子の同定および分布計測のより正確な実施を試みた。赤外吸収スペクトル情報を質量スペクトルとあわせて解析することにより、化学構造の決定および分子同定を容易とし、定量性の確保も目指した。両測定に多変量解析も適用した。

脂質、ペプチド共存系で双方を飛行時間型二次イオン質量分析法（ToF-SIMS）で正しく検出する測定条件の開発を目的とする。ToF-SIMSを用いて分布イメージを得てもマトリックッス効果によって正しいコントラストが得られるとは限らない。そこで、マトリックス効果の機構解明と補正方法を検討した。

RATIONALE: Time-of-flight secondary ion mass spectrometry (TOF-SIMS) with an Ar cluster ion beam as a primary ion source provides useful information in terms of peptide analysis. It is, however, difficult to interpret the spectra. The ToF-SIMS peptide spectra obtained with Ar clusters having different energies have been investigated in order to classify the secondary ions into the peptide fragment ions and those related to contaminants or the substrate. METHODS: Three peptides having different molecular weights from 600 to 1300 u were measured with Ar cluster beams having different energies per atom from 4 to 40 eV/atom. RESULTS: In the spectra normalized to a geometric average of all the spectra, the amino acid fragment ions are distinguished from other secondary ions. In the mass range above 600 u, the peptide fragment ions increase with mass while those not related to the peptide decrease with mass. CONCLUSIONS: Energy-dependence fragmentation helps in understanding the peptide spectra. Specific peptide fragment ions of the larger peptides are likely to be detected under lower energy than energy higher than 10 eV/atom. Although it is difficult to interpret the TOF-SIMS spectra of a peptide obtained with an Ar cluster ion beam, the secondary ions can be classified by comparing those obtained with different energy Ar cluster ion beams. Copyright (C) 2015 JohnWiley& Sons, Ltd.

Woody thin boards were prepared from lignin, cellulose, and water by compression molding at 180 degrees C and 25 MPa for 10 min. Boards with higher contact angles gave lower values of relative permittivity on their surface. Attenuated-total reflection Fourier transfer infrared spectroscopy suggested that more lignin existed on the surface of the boards with the high contact angle, which was also supported by scanning electron microscopy and atomic force microscopy. Our findings thus revealed that the orientation of lignin at the surface resulted in increased hydrophobicity of the surface and contributed to the enhancement of water repellency. (C) 2015 Published by Elsevier B.V.

We report the results of a VAMAS (Versailles Project on Advanced Materials and Standards) interlaboratory study on the measurement of composition in organic depth profiling. Layered samples with known binary compositions of Irganox 1010 and either Irganox 1098 or Fmoc-pentafluoro-L-phenylalanine in each layer were manufactured in a single batch and distributed to more than 20 participating laboratories. The samples were analyzed using argon cluster ion sputtering and either X-ray photoelectron spectroscopy (XPS) or time-of-flight secondary ion mass spectrometry (ToF-SIMS) to generate depth profiles. Participants were asked to estimate the volume fractions in two of the layers and were provided with the compositions of all other layers. Participants using XPS provided volume fractions within 0.03 of the nominal values. Participants using ToF-SIMS either made no attempt, or used various methods that gave results ranging in error from 0.02 to over 0.10 in volume fraction, the latter representing a 50% relative error for a nominal volume fraction of 0.2. Error was predominantly caused by inadequacy in the ability to compensate for primary ion intensity variations and the matrix effect in SIMS. Matrix effects in these materials appear to be more pronounced as the number of atoms in both the primary analytical ion and the secondary ion increase. Using the participants' data we show that organic SIMS matrix effects can be measured and are remarkably consistent between instruments. We provide recommendations for identifying and compensating for matrix effects. Finally, we demonstrate, using a simple normalization method, that virtually all ToF-SIMS participants could have obtained estimates of volume fraction that were at least as accurate and consistent as XPS.

飛行時間型2次イオン質量分析法(time of flight secondary ion mass spectrometry; ToF-SIMS)は，試料最表面の化学分析において最も強力な計測手法の1つである．しかし，得られるスペクトルには対象物質由来の分子イオンだけでなく，分子が分裂して生じたフラグメントイオン，基板や汚染に由来する2次イオンが多数含まれるため，結果の解釈には困難が伴う．近年，ToF-SIMSスペクトルデータの解析に多変量解析を用いる試みが広がりつつある．適切な多変量解析を行うことで，複雑なToF-SIMSスペクトルデータから有用な情報を抽出できる場合がある．本稿では，高分子多層膜断面のToF-SIMSデータへ多変量解析を適用した結果を中心に，スペクトルデータへの多変量解析の具体的な適用方法や，多変量解析によりどのような情報が得られるかについて解説する．

The evaluation of nanostructure is important to develop the highly controlled nanomaterials. In this study, two kinds of layered titanate nanosheets, which were produced by using hexylamine and laurylamine, respectively, as surfactants were investigated by Gentle Secondary Ion Mass Spectrometry Gentle-SIMS (G-SIMS) and g-ogram, which is the latest Time-of-Flight Secondary Ion Mass Spectrometry (TOF-SIMS) data analysis method for detecting more intact ions and obtaining the information on original chemical structures of samples precisely from complicated TOF-SIMS spectra. As a result, molecular related ions of the surfactants were detected from each sample, and the structural information of samples was obtained. From both samples, surfactant molecular ions connected with hydrocarbon were detected as more intact ions rather than molecular ions of themselves. It was suggested that hydrophobic domains of their lamellar mesostructure are formed robustly by more than two surfactant molecules connected with each other linearly. After all, important information on the chemical structure of the layered titanate nanosheets, which would be difficult to be found by using typical structural analysis methods such as X-ray diffraction and transmission electron microscopy, were obtained using G-SIMS and g-ogram. Therefore, it was shown that g-ogram and G-SIMS are helpful to evaluate the nanostructured materials. And it was also shown that g-ogram is applicable to organic-inorganic materials which contain long hydrocarbon structures. Copyright (c) 2015 John Wiley & Sons, Ltd.

Time-of-flight secondary ion mass spectrometry (ToF-SIMS) is a powerful tool for determining surface information of complex systems such as polymers and biological materials. However, the interpretation of ToF-SIMS raw data is often difficult. Multivariate analysis has become effective methods for the interpretation of ToF-SIMS data. Some of multivariate analysis methods such as principal component analysis and multivariate curve resolution are useful for simplifying ToF-SIMS data consisting of many components to that explained by a smaller number of components. In this study, the ToF-SIMS data of four layers of three polymers was analyzed using these analysis methods. The information acquired by using each method was compared in terms of the spatial distribution of the polymers and identification. Moreover, in order to investigate the influence of surface contamination, the ToF-SIMS data before and after Ar cluster ion beam sputtering was compared. As a result, materials in the sample of multiple components, including unknown contaminants, were distinguished. Copyright (c) 2014 John Wiley & Sons, Ltd.

Inorganic-organic composite materials are commercially utilized over a wide variety of industrial fields. The information on the distribution of inorganic and organic components on a nanometer scale is important for understanding the chemistry of the composite materials. In this study, the distribution of polycarbonate (PC) oligomer within a glass fiber reinforced PC was investigated using time-of-flight secondary ion mass spectrometry (ToF-SIMS) and principal component analysis (PCA). As a result, PCA indicated a component differentiating PC oligomer from PC polymer and revealed the homogeneous distribution of PC oligomer within the glass fiber reinforced PC. Therefore, a combination of ToF-SIMS and PCA is useful for identifying the detailed distribution of PC oligomer and evaluating the property of glass fiber reinforced PC.

巨大クラスターイオン源の開発によって、飛行時間型二次イオン質量分析 (ToF-SIMS) による測定対象が一段と広がり、金属クラスターに比べてソフトなイオン化が可能な Ar クラスターイオンなどによる測定では、高質量分子およびフラグメントイオンの検出が容易となっている。本研究では、数eVから数100eV程度の低エネルギー領域におけるエネルギーとペプチドフラグメンテーションの関係を評価した。<br>

Ａｒクラスターイオンによるスパッタリングによって、ToF-SIMSによるナノレベルでの試料の深さ方向分析が可能となった。本研究では、類似した組成の２種類の高分子の混合積層膜試料の深さ方向分析におけるマトリックル効果を評価した。データ解析では、多変量解析を適用し、それぞれの層の高分子に対応した成分を抽出できるかどうかも検討した。

High-functional plastics have been attracted much attention over the various fields of industries. For evaluating their functionalities, it is essential to investigate low molecular weight components on the surface of the plastic because these components deeply affect their functionalities. In this study, multivariate analysis and g-ogram, a G-SIMS-related spectrum analysis method, were applied to the ToF-SIMS data of polyethylene glycol mixed model sample consisting of the two different average molecular weights, 600u and 2000u (PEG600 and PEG2000). As a result, the pure component spectra suggesting PEG600, PEG2000 and polydimethylsiloxane contaminant were discriminated by using multivariate curve resolution (MCR) under the condition of reducing the chemical noise such as heavily fragmented ions and contaminants. Moreover, the major peaks of the pure component spectrum suggesting PEG2000 in MCR were the characteristic fragment ions obtained by the g-ogram result for PEG2000. Therefore, it is indicated that the combination of MCR and g-ogram methods is a promising tool for evaluating the functionalities of the high-functional plastics. Copyright (c) 2014 John Wiley & Sons, Ltd.

In this study, tendencies of ionization and cleavage processes of time-of-flight (TOF)-SIMS were examined using MS/MS, which enables an easy qualitative analysis of organic matters, to clarify the fragment ions showing structures of the organic materials. In this paper, a result of reviewing fragment ions in TOF-SIMS spectra for polystyrene (PS) as the representative material is shown. Samples were measured with collision induced dissociation (CID)-MS/MS of 1200L (Varian Inc., USA) and TOF-SIMS J105 (Ionoptika Ltd, UK) for the examination of fragment ions of the PS in TOF-SIMS spectra. The use of CID MS/MS with a wide range of energy distribution is effective for the study of the ionization and cleavage process of TOF-SIMS. As a result, the fragment ions representing the PS structure were clarified, which is useful for the material definition. The qualitative analysis was also applied to the fragment ions particularly obtained in this examination. It is suggested that the examination of the fragmentation process using MS/MS is useful for the mass spectra analysis of organic materials in TOF-SIMS. Copyright (c) 2014 John Wiley & Sons, Ltd.

A novel method with quaternary ammonium salts as internal additives has been applied to the mass-scale calibration of time-of-flight secondary ion mass spectrometry (TOF-SIMS). Five kinds of quaternary ammonium salts, octyltrimethylammonium bromide (C8TMA), tetradecyltrimethylammonium chloride (C14TMA), octadecyltrimethylammonium chloride (C18TMA), cetylpyridinium chloride (CPC) and benzyldimethyltetradecylammonium chloride (Bzl) were diluted with NH3 aqueous solution and were mixed in equal quantities. The mixed solution was covered on a Si wafer and was measured by TOF-SIMS. When molecular ions of C8TMA, C14TMA, and C18TMA were used for the mass-scale calibration, the relative mass accuracy of low-mass CXHY fragment ions indicated negative values and depended on the carbon chain length and the degree of unsaturation. This result means that the conventional mass-scale calibration with frequently employed low-mass CXHY fragment ions leads to degradation of the mass accuracy of high-mass molecular ions. To improve the mass accuracy of molecular ions of CPC and Bzl, ions should be selected for the mass-scale calibration in the following two ways: One way is for ions to consist only of molecular ions of C8TMA, C14TMA, and C18TMA, and the other way is for ions to include one of the molecular ions: C8TMA, C14TMA, and C18TMA, along with the CXHY fragment ions. This novel mass-scale calibration method is promising for realizing the correct identification of unknown high-mass molecular ions. Those quaternary ammonium salts are powerful candidates of internal additives. Copyright (c) 2014 John Wiley & Sons, Ltd.

Recently, controlled production of plants to enhance specific ingredients, such as sinigrin in Wasabi effective for antibacterial and anticancer, in the plants has become more important in order to use the ingredients efficiently. It is, however, difficult to develop a plant production method for controlling the sinigrin amount, because the sinigrin production mechanism is not clear. Therefore, it is crucial to evaluate distribution and metabolic pathways of sinigrin and related molecules in the wasabi tissue. Because time-of-flight (ToF)-SIMS provides molecular distributions of insulation samples including plant tissues on a submicron scale, it is useful for such a purpose. On the other hand, interpretation of intricate ToF-SIMS spectra of complex samples is often difficult. Recently, multivariate analysis techniques, such as principal component analysis and multivariate curve resolution, successfully applied into a variety of scientific fields have been also introduced into ToF-SIMS data. Moreover, gentle secondary ion mass spectrometry (G-SIMS), developed for analyzing static-SIMS spectra in terms of the degree of fragmentation, has recently been applied to various samples. In this study, sections of Wasabi petioles were evaluated with ToF-SIMS and the data analysis techniques to clarify the distribution of sinigrin molecule in the wasabi tissue. A combination of multivariate analysis and G-SIMS worked effectively to interpret the complex ToF-SIMS data of the plant tissue. As a result, the detailed distribution of sinigrin in the plant tissue was indicated by ToF-SIMS and the data analysis techniques. Copyright (c) 2014 John Wiley & Sons, Ltd.

A novel application of time-of-flight secondary ion mass spectrometry (ToF-SIMS) with continuous Ar cluster beams to peptide analysis was investigated. In order to evaluate peptide structures, it is necessary to detect fragment ions related to multiple neighbouring amino acid residues. It is, however, difficult to detect these using conventional ToF-SIMS primary ion beams such as Bi cluster beams. Recently, C-60 and Ar cluster ion beams have been introduced to ToF-SIMS as primary ion beams and are expected to generate larger secondary ions than conventional ones. In this study, two sets of model peptides have been studied: (des-Tyr)-Leu-enkephalin and (des-Tyr)-Met-enkephalin (molecular weights are approximately 400 Da), and [Asn(1) Val(5)]-angiotensin II and [Val(5)]-angiotensin I (molecular weights are approximately 1,000 Da) in order to evaluate the usefulness of the large cluster ion beams for peptide structural analysis. As a result, by using the Ar cluster beams, peptide molecular ions and large fragment ions, which are not easily detected using conventional ToF-SIMS primary ion beams such as Bi-3 (+), are clearly detected. Since the large fragment ions indicating amino acid sequences of the peptides are detected by the large cluster beams, it is suggested that the Ar cluster and C-60 ion beams are useful for peptide structural analysis.