• Bulletin of the Korean Chemical Society
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• v.25 no.2
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• pp.226-232
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• 2004

Ground and low-lying electronic states of Cr atoms in the gas phase were generated from photolysis of $Cr(CO)_6$ vapor in He or Ar using an unfocussed weak UV laser pulse and their reactions with $O_2$ and $N_2O$ were studied. When 0.5-1.0 Torr of $Cr(CO)_6$ /$O_2$ /He or Ar mixtures were photolyzed using 295-300 nm laser pulses, broadband chemiluminescence peaked at ~420 and ~500 nm, respectively, was observed in addition to the atomic emissions from $z^7P^{\circ}$, $z^5P^{\circ}$, and $y^7P^{\circ}$ states of Cr atoms. When $N_2O$ was used instead of $O_2$, no chemiluminescence was observed. The chemiluminescence intensities as well as the LIF intensities for those three low-lying electronic states ($a^7S_3,\;a^5S_2\;and\;a^5D_J$) showed second-order dependence on the photolysis laser power. Also, the chemiluminescence intensities were first-order in $O_2$ pressure, but the presence of excess Ar showed a strong inhibition effect on them. Based on the experimental results, the chemiluminecent species in this work is attributed to $CrO_2^*$ generated from hot ground state Cr atoms with $O_2$. The apparent radiative lifetimes of the chemiluminescent species and collisional quenching rate constants by $O_2$ and Ar also were investigated.

• Transactions on Electrical and Electronic Materials
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• v.16 no.5
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• pp.264-267
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• 2015

AlCrNO cermet films were prepared on aluminum substrates using a DC-reactive magnetron sputtering method and a water-cooled Al:Cr target. The Al₂O₃/AlCrNO (LMVF)/AlCrNO (MMVF)/AlCrNO (HMVF)/Al/substrate of the 5 multi-layers was prepared according to the Ar and (N₂ + O₂) gas-mixture rates. The Al₂O₃ of the top layer is the anti-reflection layer of triple AlCrNO (LMVF)/AlCrNO (MMVF)/AlCrNO (HMVF) layers, and an Al metal forms the infrared reflection layer. In this study, the crystallinity and surface properties of the AlCrNO thin films were estimated using X-ray diffraction (XRD) and field-emission scanning electron microscopy (FESEM), while the composition of the thin films was systematically investigated using Auger electron spectroscopy (AES). The optical properties of the wavelength spectrum were recorded using UH4150 spectrophotometry (UV-Vis-NIR) at a range of 0.3 μm to 2.5 μm.

• Journal of the Korean Institute of Gas
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• v.8 no.1 s.22
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• pp.37-47
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• 2004

Pressure swing adsorption (PSA) process using CMS as an oxygen purifier was developed to produce high purity oxygen over $99\%$ with high productivity. The cyclic performances such as purity, recovery, and productivity of PSA process were compared experimentally and theoretically under the non-isothermal condition. A binary ($O_2$/Ar 95:5 vol.$\%$) and two kinds of ternary ($O_2/Ar/N_2$ 95:4:1 and 90:4:6 vol.$\%$) mixtures were used as feed gases. The developed process with the consecutive two blowdown steps produced the oxygen with $99.8\%$ purity and $56\%$ recovery from $95\%$ oxygen containing feed. However, in the feed with $90\%$ oxygen, the $O_2$ Purity was decreased up to $97.3\%$. In addition, because the cyclic performances of the suggested process was significantly affected by the diffusion rate, the non-isothermal model with the the modified LDF model was applied for the process simulation. The concentration-dependent rate parameter of the applied rate model was incorporated with the Langmuir isotherm.

• Transactions on Electrical and Electronic Materials
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• v.2 no.1
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• pp.7-11
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• 2001

We measured the electron transport coefficients, the electron drift velocity, W, and the longitudinal diffusion coefficient, $D_{L}$, over the E/N range from 0.03 to 100 Td and gas pressure range from 0.133 to 122 kPa in the 0.526% and 5.05% $C_{3}F_{8}$-Ar mixtures by the double shutter drift tube with variable drift distance. And we calculated these electron transport coefficients by using multi-term approximation of Boltzmann equation analysis. We determined the electron collision cross sections set for $C_{3}F_{8}$ molecule by the comparison of measurement and calculation. Our special attention in the present study was focused upon the inelastic collision cross sections of the $C_{3}F_{8}$ molecule.

• Journal of the Korean institute of surface engineering
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• v.35 no.6
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• pp.415-421
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• 2002

Ti-Si-N coating layers were codeposited on silicon wafer substrates by a DC reactive magnetron sputtering technique using separate titanium and silicon targets in $N_2$/Ar gas mixtures. The oxidation behavior of Ti-Si-N coating layers containing 4.0 at.%, 10.0 at.%, and 27.3 at.% Si was investigated at temperatures ranging from 600 to $960^{\circ}C$. The coating layers containing 4.0 at.% Si became fast oxidized from $600^{\circ}C$ while the coating layers containing 10.0 at.% Si had oxidation resistance up to $800^{\circ}C$. It was concluded that an increase in Si content to a level of 10.0 at.% led to the formation of finer TiN grains and a uniformly distributed amorphous Si3N4 phase along grain boundaries, which acted as efficient diffusion barriers against oxidation. However, the coating layers containing 27.3 at.% Si showed relatively low oxidation resistance compared with those containing 10.0 at.% Si. This phenomenon would be explained by the existence of free Si which was not nitrified in the coating layers containing 27.3 at.% Si.