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Sub-target effect in film analysis using TEA CO2 laser-induced plasma
Yong-Inn Lee,Nasrullah Idris,Koo Hendrik Kurniawan,Tjung Jie Lie,Kenichiro Tsuyuki,Satoru Miura,Kiichiro Kagawa 한국물리학회 2007 Current Applied Physics Vol.7 No.5
A bioactive and biodegradable composite material consisting of hydroxyapatite (HA) and polyhydroxybutyrate (PHB) was investi-PHB composite which contained up to 40% by volume of particulate HA. The processing parameters for composite manufacture wereoptimized through thermal analyses of HA/PHB composite produced and production trials. The microstructure and properties of thecomposite were evaluated using various techniques. Form the results obtained, it is shown that good quality HA/PHB composite prod-ucts could be manufactured via the established production route.
Confinement Effect in TEA CO2 Laser-Induced Plasma on Solid Organic Samples
Nasrullah Idris,Yong-Inn Lee,Hendrik Kurniawan,Kiichiro Kagawa,Maria Margaretha Suliyanti,Takao Kobayashi,Tjung Jie Lie 한국물리학회 2005 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.47 No.1
A Transversely Excited Atmospheric (TEA) CO2 laser beam (500 mJ, 200 ns) was focused on soft solid organic compounds under a low-pressure surrounding gas at around 2 Torr. We found that in order to induce a laser plasma from solid organic sample, such as plastics, the ablated atoms must be confined in a small hole (diameter of about 1 mm and depth of around 1 − 2 mm). Using our unique technique of density jump measurement (Rainbow Interferometer), we proved that the plasma is excited by a shock wave and that the confining hole works to induce and enhance a strong shock wave. The plasma has favorable characteristics for spectrochemical analysis due to its low spectral background and sharp emission lines; hence, the spectra can be taken using optical multichannel analyzer (OMA) without gated mode. By using the confinement effect, we detected chlorine ionic lines (Cl II at 479.4 nm, Cl II at 481.0 nm, and Cl II at 481.9 nm) with relatively strong emission intensities in the plastic sample containing chlorine.
Zener Sukra Lie,Ali Khumaeni,Hideaki Niki,Kazuyoshi Kurihara,Koo Hendrik Kurniawan,Rinda Hedwig,Ken-ichi Fukumoto,Kiichiro Kagawa,이용인 한국물리학회 2012 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.61 No.1
Our previous work on an innovative method of hydrogen (H) analysis using the specific characteristics of a TEA CO<sub>2</sub> laser, 뱒elective detection method of H? has been improved to realize a high H sensitive analysis with a detection limit of several 킽/g. For this purpose, first, we clarified the origin of the H emission disturbance coming from H<sub>2</sub>O molecules; namely, we showed that most of the H emission came from H<sub>2</sub>O on the metal surface and not from H<sub>2</sub>O existing in the surrounding gas when we formed a laser-induced gas plasma. Second, the difference in the emission characteristics between the H emission from H<sub>2</sub>O on the metal surface and H emission from inside in sample was studied to determine the optimum gating time of the optical multi-channel analyzer (OMA). Third, the gas plasma was totally covered by fresh helium gas using a big pipe (5 mm in diameter) and by flowing a high amount of He (10 l/min). Also, we demonstrated that our methods could potentially be applied to H analysis in steel samples, where an H analysis with a sensitivity of less than 1 킽/g is required without employing a heating process, by removing H<sub>2</sub>O on the sample surface with the aid of defocused TEA CO<sub>2</sub> laser irradiation. Thus, we stress that our method can be used for a highly sensitive, <i>in-situ</i> analysis of H for metal samples.
Nasrullah IDRIS,Yong Inn LEE,Kiichiro KAGAWA,Koo Hendrik KURNIAWAN 한국물리학회 2007 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.51 No.2I
An electromagnetic phenomenon in terms of the induced current in a laser ablation process has been studied, and its potential application has been demonstrated. A new electrode configuration for measuring the induced current emerged due to the interaction between the electric lines of force and the laser-produced plasma has been devised. In this new electrode configuration, the induced current is detected by employing a circuit of electrodes, supplied with several hundred DC volts and placed above the sample surface in parallel, which is called the parallel configuration. This parallel configuration provides a far higher flexibility in comparison with the sandwiched configuration developed in our previous work. The induced current signal can be detected from various samples of any size, including metals and nonmetals. We found that the source of the induced current was the outer electrons in the plasma. This induced current is very useful as a unique monitoring method and promises many applications in laser microprocessing. In this work, this induced current method was applied for several monitoring purposes in laser material processing, such as for estimating the ablated amount, monitoring the penetration of a laser beam into processed materials, and determining the precise tight focusing position of the lens, in real time.
M. M. Suliyanti,M. Pardede,Tjung Jie Lie,Koo Hendrik Kurniawan,Ali Khumaeni,Kiichiro Kagawa,May On Tjia,이용인 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.58 No.5
The direct analysis of powder samples has been carried out successfully by utilizing lasercontrolled dust production in a small chamber pressurized to one atmosphere with He. A 355-nm Nd:YAG laser (5 mJ, 10 Hz) was focused on the surface of the powder sample to form a microplasma, which released a tiny amount of powder in the form of a dust. A 1064-nm Nd:YAG laser operating at higher energy (110 mJ, 10 Hz), which is not synchronized with the 355-nm Nd:YAG laser, was then used to form a He gas breakdown plasma in the dust region to atomize and excite the dust. We assumed that this excitation process involved metastable He atoms produced in the breakdown plasma. The emission spectra obtained for a variety of powder samples by using this method were found to be of good quality. Furthermore, the method can be used to analyze liquid samples by placing a drop of liquid onto a small piece of cotton to avoid splashing. Indeed, the rapid and semi-quantitative analysis of both powder and liquid samples has proved to be possible using the present technique. One advantage of this technique is that analyses can be conducted even when the samples are available in only very small amounts.