• Mass Spectrometry Letters
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• v.2 no.1
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• pp.8-11
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• 2011

Two types of glycerolipids [monoacylglycerols (MAG) and cyclitols] were isolated by reversed phase high-performance liquid chromatography from the methanol extracts of a marine sponge, and analyzed by fast atom bombardment mass spectrometry (FAB-MS) in positive-ion mode. FAB mass spectra of these compounds yielded protonated molecules $[M + H]^+$ and abundant sodiated molecules $[M + Na]^+$ from a mixture of 3-nitrobenzyl alcohol and NaI. The structures of these compounds were elucidated by FAB-collisional-induced dissociation (CID)-tandem mass spectrometry. We carried out collision-indused dissociation (CID) of these lipids in B/E-linked scan mode. The CID B/E-linked scan of $[M + H]^+$ and $[M + Na]^+$ precursor ions resulted in the formation of numerous characteristic product ions through a series of dissociative processes. The product ions formed by charge-remote fragmentation (CRF) provided important information for the identification of the acyl chain structure substituted at the glycerol backbone. Some of the product the ions were diagnostic for the presence of a glycerol backbone or acyl chain structure.

• Bulletin of the Korean Chemical Society
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• v.18 no.8
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• pp.874-880
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• 1997

Various classes of phospholipids were investigated for the structural determination of fatty acyl groups by fast atom bombardment tandem mass spectrometry (FAB-MS/MS). Phospholipids were desorbed by FAB as molecules chelated with sodium ion (or ions). Collision-induced dissociation (CID) of intact sodium adduct molecular ions ([M+Na]+, [M-H+2Na]+ or [M+Na-2H]-) produced a series of homologous fragment ions via the charge-remote fragmentation along the fatty acid chains. These ions were found useful to locate the double bond positions even for the polyunsaturated fatty acid chains. The regiospecificity of the acyl chain linkages in phosphatidylcholine (PC) could also be determined based on the ratio of relative abundance of the product ions (i.e., [M+Na-85-R2COOH]+ vs [M+Na-85-R1COOH]+) in CID-MS/MS of [M+Na]+. These are generated by the loss of fatty acyl groups at sn-1 and sn-2, respectively, together with the choline group. In all the phospholipid compounds investigated, loss of the fatty acid at the sn-2 position was dominant. The present method was applied to the structural determination of molecular species of phosphatidylglycerols (PG) isolated from cyanobacterium Synechocystis sp. PCC 6803.

• Transactions on Electrical and Electronic Materials
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• v.18 no.2
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• pp.74-77
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• 2017

In this work, we investigated the etching characteristics of TaNO thin films and the selectivity of TaNO to $SiO_2$ in an $O_2$/CF4/Ar inductively coupled plasma (ICP) system. The maximum etch rate of TaNO thin film was 297.1 nm/min at a gas mixing ratio of O2/CF4/Ar (6:16:4 sccm). At the same time, the etch rate was measured as a function of the etching parameters, such as the RF power, DC-bias voltage, and process pressure. X-ray photoelectron spectroscopy analysis showed the efficient destruction of the oxide bonds by the ion bombardment, as well as the accumulation of low volatile reaction products on the etched surface. Based on these data, the ion-assisted chemical reaction was proposed as the main etch mechanism for the $CF_4$-containing plasmas.

• Journal of the Speleological Society of Korea
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• no.82
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• pp.1-4
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• 2007

In this paper, the etching of Au films using photoresist masks on Si substrates was investigated using a capacitively coupled plasma etch reactor. The advantages of plasma etch techniques over current methods for Au metalization include the ability to simplify the metalization process flow with respect to resist lift-off schemes, and the ability to cleanly remove etched material without sidewall redeposition, as is seen in ion milling. The etch properties were measured for different gas mixing ratios of CF4/Ar, and chamber pressures while the other conditions were fixed. According to statistical design of experiment (DOE), etching process of Au films was characterized and also 20 samples were fabricated followed by measuring etch rate, selectivity and etch profile. There is a chemical reaction between CF4 and Au. Au- F is hard to remove from the surface because of its high melting point. The etching products can be sputtered by Ar ion bombardment.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07a
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• pp.58-61
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• 2002

SBT thin films were etched at different content of Cl$_2$in Cl$_2$/Ar plasma. We obtained the maximum etch rate of 883 ${\AA}$/min at Cl$_2$(20%)/Ar(80%). As Cl$_2$ gas increased in Cl$_2$/Ar plasma, the etch rate decreased. The maximum etch rate may be explained by variation of volume density for Cl atoms and by the concurrence of two etching mechanisms such as physical sputtering and chemical reaction with formation of low-volatile products, which can be desorbed only by ion bombardment. The variation of volume density for Cl, F and Ar atoms and ion current density were measured by the optical emission spectroscopy and Langmuir probe. To evaluate the physical damage due to plasma, X-ray diffraction and atomic force microscopy analysis carried out. After etching process, P-E hysteresis loops were measured by ferroelectric workstation.

• Journal of the Korean Ceramic Society
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• v.31 no.5
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• pp.485-490
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• 1994

The reactive ion etching characteristics of aluminum oxide films, prepared by PECVD, were investigated in the CCl4 plasma. The atomic chlorine concentration and the DC self bias were determined at various etching conditions, and their effects on the etch rate of aluminum oxide film were studied. The bombarding energy of incident particles was found to play the more important role in determining the etch rate of aluminum oxide rather than the atomic chlorine concentration. It is considered to be because the bombardment of ions or neutral atoms breaks the strong Al-O bonds of aluminum oxide to help activate the formation reaction of AlCl3 which is the volatile etch product.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1999.10a
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• pp.197-203
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• 1999

Stainless steels in general has passive film having strong corrosion resistance on surface. Therefore it must be necessarily removed by etching in mixing solution of sulfuric and chloric acid before Nitriding treatment. But in the ion nitriding, nitride layer was easily formed because passive film was removed without difficult by sputtering effect. The removal extent of these passive films was greatly effected by gas mixing ratios and pressure and holding times of pre sputtering factors in pre sputtering stage. As a results of experiment it has been known that pre sputtering pressure and holding time was not nearly effective on the formation behavior of nitride layer. But when A/H2 gas mixing ratios was 1/2 (vol%) was the most effective of the all pre sputtering conditions. It was resulted from the combination of mechanical reaction byArgon bombardment and chemical reaction by reduction of hydrogen on the passive film.

• Transactions on Electrical and Electronic Materials
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• v.13 no.1
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• pp.6-9
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• 2012

In this study, we carried out an investigation of the etching characteristics (etch rate, selectivity to $SiO_2$) of ZnO thin films in $N_2/Cl_2$/Ar inductivity coupled plasma. A maximum etch rate and selectivity of 108.8 nm/min and, 3.21, respectively, was obtained for ZnO thin film at a $N_2/Cl_2$/Ar gas mixing ratio of 15:16:4 sccm. The plasmas were characterized by optical emission spectroscopy. The x-ray photoelectron spectroscopy analysis showed the efficient destruction of oxide bonds by ion bombardment. An accumulation of low volatile reaction products on the etched surface was also shown. Based on this data, an ion-assisted chemical reaction is proposed as the main etch mechanism for plasmas containing $Cl_2$.

• Journal of the Korean institute of surface engineering
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• v.39 no.3
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• pp.105-109
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• 2006

The effects of negative carbon ion beam energy on the bonding configuration, hardness and surface roughness of DLC film prepared by a direct metal ion beam deposition system were investigated. As the negative carbon ion beam energy increased from 25 to 150 eV, the $sp^3$ fraction of DLC films was increased from 32 to 67%, while the surface roughness was decreased. The films prepared at 150 eV showed the more flat surface morphology of the film than that of the film prepared under another ion beam energy conditions. Surface roughness of DLC film varied from 0.62 to 0.22 nm with depositing carbon ion beam energy. Surface nano-hardness increased from 12 to 57 Gpa when increasing the negative carbon ion beam energy from 25 to 150 eV, and then decreased when increasing the ion beam energy from 150 to 200 eV.

• Journal of the Korean Vacuum Society
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• v.16 no.4
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• pp.250-261
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• 2007

We present the morphological evolution at different source powers in the ion-enhanced etching of GaAs(100) in $BCl_3-Cl_2$ plasma. With little ion bombardment at floating potential, the surface develops <110> ridges and {111} facets, as it does in purely chemical etching. Higher source power (900 W) produces well developed crystallographic surfaces while lower source power (100 W) produces poorly developed crystallographic surfaces. This is attributed to the availability of excited reactive species (chlorine atoms) depending on source powers. With more concentration of the reactive species at higher source powers, the surface of GaAs(100) would be a surface that is expected from thermodynamics while the surface morphology would be determined by sputtering in the lack of reactive species. Statistical analysis of the surfaces, based on scaling theory, revealed two spatial exponents: one (smaller than one) is formed by atomic scale mechanisms, the other (larger than one) is formed by larger scale mechanisms which is believed to develop facets. When samples are biased, the surfaces experienced bombardment resulting in suppression of ridge formation at high source power and islands formation at low source power.