• Mass Spectrometry Letters
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• v.14 no.4
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• pp.147-152
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• 2023

The increasing demand for two-dimensional imaging analysis using optical or electronic microscopic techniques has led to an increase in the use of simple one-dimensional and two-dimensional mass spectrometry imaging. Among these imaging methods, secondary-ion mass spectrometry (SIMS) has the best spatial resolution using a primary ion beam with a relatively insignificant beam diameter. Until recently, SIMS, which uses high-energy primary ion beams, has not been used to analyze molecules. However, owing to the development of cluster ion beams, it has been actively used to analyze various organic molecules from the surface. Researchers and commercial SIMS companies are developing cluster ion beams to analyze biological samples, including amino acids, peptides, and proteins. In this study, a water droplet ion beam for surface analysis was realized. Water droplets ions were generated via electrospraying in a vacuum without desolvation. The generated ions were accelerated at an energy of 10 keV and collided with the target sample, and secondary ion mass spectra were obtained for the generated ions using ToF-SIMS. Thus, the proposed water droplet ion-beam device showed potential applicability as a primary ion beam in SIMS.

• Journal of Radiation Protection and Research
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• v.48 no.4
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• pp.204-212
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• 2023

Background: Isotopes of the projectile may be produced along the beam path during the irradiation of a target by a heavy ion due to inelastic interactions with the media. This study analyzed the production cross-section of carbon (C) and Helium (He) projectile's isotopes resulting from the interactions of these beams with different materials along the beam path. Materials and Methods: In this study, we transport C and He ion beams through different materials. This transportation was made by the Monte Carlo simulation. Particle and Heavy Ion Transport code System (PHITS) has been used for this calculation. Results and Discussion: It has been found that ¹⁰C, ¹¹C, and ¹³C from the ¹²C ion beam and ³He from the ⁴He ion beam are significant projectile's isotopes that have higher flux than other isotopes of these projectiles. The ⁴He ion beam has a higher projectile's isotope production cross-section along the beam path, which adds more impurities to the beam than the ¹²C ion beam. These projectile's isotopes from both the ¹²C and ⁴He ion beams have higher production cross-sections in hydrogenous materials like water or polyethylene. Conclusion: It is important to distinguish these projectile's isotopes from the primary beam particles to obtain a precise and accurate cross-section result by minimizing the error during measurement with a nuclear track detector. This study will show the trend of the production probability of projectile's isotopes for these ion beams.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.16 no.2
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• pp.70-77
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• 2007

The application of focused ion beam(FIB) technology has been broadened in the fabrication of nanoscale regime. The extended application of FIB is dependent on complicated reciprocal relation of operating parameters. It is necessary for successful and efficient modifications on the surface of silicon substrate. The primary effect by Gaussian beam intensity is significantly shown from various aperture size, accelerating voltage, and beam current. Also, the secondary effect of other process factors - dwell time, pixel interval, scan mode, and pattern size has affected to etching results. For the process analysis, influence of the secondary factors on FIB micromilling process is examined with respect to sputtering depth during the milling process in silicon material. The results are analyzed by the ratio of signal to noise obtained using design of experiment in each parameter.

• Proceedings of the Korea Association of Crystal Growth Conference
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• 1996.06a
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• pp.5-18
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• 1996

The solid state cesium ion source os alumino-silicate based zeolite which contains cerium. The material is an ionic conductor. Cesiums are stably stored in the material and one can extract the cesiums by applying electric field across the electrolyte. Cesium ion bombardment has the unique property of producing high negative ion yield. This ion source is used as the primary source for the production of a negative ion without any gas discharge or the need for a carrier gas. The deposition of materials as an ionic species in the energy range of 1.0 to 300eV is recently recognized as a very promising new thin film technique. This energetic non-thermal equilibrium deposition process produces films by “Kinetic Bonding / Energetic Condensation" mechansim not governed by the common place thermo-mechanical reaction. Under these highly non-equilibrium conditions meta-stable materials are realized and the negative ion is considered to be an optimum paeticle or tool for the purpose. This process differs fundamentally from the conventional ion beam assisted deposition (IBAD) technique such that the ion beam energy transfer to the deposition process is directly coupled the process. Since cesium ion beam sputter deposition process is forming materials with high kinetic energy of metal ion beams, the process provider following unique advantages:(1) to synthesize non thermal-equilibrium materials, (2) to form materials at lower processing temperature than used for conventional chemical of physical vapor deposition, (3) to deposit very uniform, dense, and good adhesive films (4) to make higher doposition rate, (5) to control the ion flux and ion energy independently. Solid state cesium ion beam sputter deposition system has been developed. This source is capable of producing variety of metal ion beams such as C, Si, W, Ta, Mo, Al, Au, Ag, Cr etc. Using this deposition system, several researches have been performed. (1) To produce superior quality amorphous diamond films (2) to produce carbon nitirde hard coatings(Carbon nitride is a new material whose hardness is comparable to the diamond and also has a very high thermal stability.) (3) to produce cesiated amorphous diamond thin film coated Si surface exhibiting negative electron affinity characteristics. In this presentation, the principles of solid state cesium ion beam sputter deposition and several applications of negative metal ion source will be introduced.

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.119-119
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• 2015

Ion beam sputtering has been widely used in Secondary Ion Mass Spectrometry (SIMS), X-ray Photoelectron Spectroscopy (XPS), and Auger Electron Spectroscopy (AES) for depth profile or surface cleaning. However, mainly due to severe matrix effects such as surface composition change from its original composition and damage of the surface generated by ion beam bombardment, conventional sputtering skills using mono-atomic primary ions with energy ranging from a few hundred to a thousand volts are not sufficient for the practical surface analysis of next-generation organic/inorganic device materials characterization. Therefore, minimization of the surface matrix effects caused by the ion beam sputtering is one of the key factors in surface analysis. In this work, the electronic structure of a $Ta_2O_5$ thin film on $SiO_2/Si$ (100) after Ar Gas Cluster Ion Beam (GCIB) sputtering was investigated using X-ray photoemission spectroscopy and compared with those obtained via mono-atomic Ar ion beam sputtering. The Ar ion sputtering had a great deal of influence on the electronic structure of the oxide thin film. Ar GCIB sputtering without sample rotation also affected the electronic structure of the oxide thin film. However, Ar GCIB sputtering during sample rotation did not exhibit any significant transition of the electronic structure of the $Ta_2O_5$ thin films. Our results showed that Ar GCIB can be useful for potential applications of oxide materials with sample rotation.

• Bulletin of the Korean Chemical Society
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• v.34 no.3
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• pp.815-819
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• 2013

Micropatterns of streptavidin and human epidermal carcinoma A431 cells were successfully imaged, as received and without any labeling, using cluster $Au_3{^+}$ ion beam-based time-of-flight secondary ion mass spectrometry (TOF-SIMS) together with a principal component analysis (PCA). Three different analysis ion beams ($Ga^+$, $Au^+$ and $Au_3{^+}$) were compared to obtain label-free TOF-SIMS chemical images of micropatterns of streptavidin, which were subsequently used for generating cell patterns. The image of the total positive ions obtained by the $Au_3{^+}$ primary ion beam corresponded to the actual image of micropatterns of streptavidin, whereas the total positive-ion images by $Ga^+$ or $Au^+$ primary ion beams did not. A PCA of the TOF-SIMS spectra was initially performed to identify characteristic secondary ions of streptavidin. Chemical images of each characteristic ion were reconstructed from the raw data and used in the second PCA run, which resulted in a contrasted - and corrected - image of the micropatterns of streptavidin by the $Ga^+$ and $Au^+$ ion beams. The findings herein suggest that using cluster-ion analysis beams and multivariate data analysis for TOF-SIMS chemical imaging would be an effectual method for producing label-free chemical images of micropatterns of biomolecules, including proteins and cells.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.269-269
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• 2012

A new ion source has been designed, fabricated, and installed at the NBTS (Neutral Beam Test Stand) at the KAERI (Korea Atomic Energy Research Institute) site. The goalis to provide a 100 keV, 2MW deuterium neutral beam injection as an auxiliary heating of KSTAR (Korea Super Tokamak Advanced Research). To cope with power demand, an ion current of 50 A is required considering the beam power loss and neutralization efficiency. The new ion source consists of a magnetic cusp bucket plasma generator and a set of tetrode accelerators with circular copper apertures. The plasma generator for the new ion source has the same design concept as the modified JAEA multi-cusp plasma generator for the KSTAR prototype ion source. The dimensions of the plasma generator are a cross section of $59{\times}25cm^2$ with a 32.5 cm depth. The anode has azimuthal arrays of Nd-Fe permanent magnets (3.4 kG at surface) in the bucket and an electron dump, which makes 9 cusp lines including the electron dump. The discharge properties were investigated preliminarily to enhance the efficiency of the beam extraction. The discharge of the new ion source was mainly controlled by a constant power mode of operation. The discharge of the plasma generator was initiated by the support of primary electrons emitted from the cathode, consisting of 12 tungsten filaments with a hair-pin type (diameter = 2.0 mm). The arc discharge of the new ion source was achieved easily up to an arc power of 80 kW (80 V/1000 A) with hydrogen gas. The 80 kW capacity seems sufficient for the arc power supply to attain the goal of arc efficiency (beam extracted current/discharge input power = 0.8 A/kW). The accelerator of the new ion source consists of four grids: plasma grid (G1), gradient grid (G2), suppressor grid (G3), and ground grid (G4). Each grid has 280 EA circular apertures. The performance tests of the new ion source accelerator were also finished including accelerator conditioning. A hydrogen ion beam was successfully extracted up to 100 keV /60 A. The optimum perveance is defined where the beam divergence is at a minimum was also investigated experimentally. The optimum hydrogen beam perveance is over $2.3{\mu}P$ at 60 keV, and the beam divergence angle is below $1.0^{\circ}$. Thus, the new ion source is expected to be capable of extracting more than a 5 MW deuterium ion beam power at 100 keV. This ion source can deliver ~2 MW of neutral beam power to KSTAR tokamak plasma for the 2012 campaign.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1994.05a
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• pp.113-115
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• 1994

We considered the ion and photo-induced properties as a function of wavelength by exposing the light over the band gap of a-Ag/a-$Se_{75}$$Ge_{25}$ and the low-energy defocused $Ga^{+}$ ion beam on Ag/a-$Se_{75}$$Ge_{25}$ thin film. This film acts as a negative resist for photo or ion beam lithography. We observed that the absorbance coefficient decreased with increasing the photo-exposing time and exposing the ion beam. The bandgap shifts toward longer wavelength called a "darkening effect" are observed in the films exposed to both photons and ions. We suggest that a primary step in the Ag layer and a secondary step is in a-$Se_{75}$$Ge_{25}$ film layer.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.05a
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• pp.329-334
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• 2002

Preliminary test for the design and construction of a tuned dynamic absorber is a conducted. Proposed tuned dynamic absorber is a cantilevered beam type, and is supposed to adjust its natural frequency according to the changing operation condition of the primary system. The modal mass of the dynamic absorber is the easiest to control, therefore, the position of the attached mass of the dynamic absorber is considered as the main design parameter of the absorber. The effect of the dynamic absorber is experimentally verified under various operation conditions of the primary system.

• Applied Microscopy
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• v.41 no.3
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• pp.147-154
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• 2011

Backscattered electrons (BSE) are generated at the impact of the primary electron beam on the specimen. BSE imaging provides the compositional contrast to resolve chemical features of sectioned block-face. A focused ion beam (FIB) column can be combined with a field emission scanning electron microscope (FESEM) to ensure a dual (or cross)-beam system (FIB-FESEM). Due to the milling of the specimen material by 10 to 100 nm with the gallium ion beam, FIB-FESEM allows the serial block-face (SBF) imaging of plastic-embedded specimens with high z-axis resolution. After contrast inversion, BSE images are similar to transmitted electron images by transmission electron microscopy. As another means of SBF imaging, a specialized ultramirotome has been incorporated into the specimen chamber of FESEM ($3View^{(R)}$). Internal structures of plastic-embedded specimens can be serially revealed and analyzed by $3View^{(R)}$ with a large field of view to facilitate three-dimensional reconstruction. These two SBF approaches by FESEM can be employed to unravel spatial association of (sub)cellular entities for a comprehensive understanding of complex biological systems.