• 분석과학
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• 제22권2호
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• pp.152-158
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• 2009

본 연구에서는 유기화합물의 효과적인 소프트 이온화를 위하여 기존의 SPI장치를 개선한 새로운 형태의 방전 장치를 제작하였다. 새로 제작된 소프트 플라스마 이온화 장치는 반 원통 형태의 메쉬 음극과 속빈 원통 형태의 양극으로 구성하였다. 이온화원으로 사용하기에 앞서, 특정압력에서 전극간격에 따른 전압 전류 특성곡선을 조사하여 장치의 구성을 최적화 하였으며, 그 결과 넓은 전압 전류 영역에서 안정한 플라스마를 생성하는 조건을 결정하여 다양한 이온화 패턴을 기대 할 수 있게 하였다. 최적화된 이온화장치를 사중극자 질량분석기와 연결하여 디클로로메탄의 질량 스펙트럼을 관찰하였고, 분석결과 디클로로메탄은 전자충격이온화에 의한 분리 패턴과 비슷하게 나타나는 것을 확인하였다.

• Mass Spectrometry Letters
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• 제6권3호
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• pp.71-74
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• 2015

Low temperature plasma (LTP) ionization mass spectrometry (MS) is one of the widely used ambient analysis methods which allows soft-ionization and rapid analysis of samples in ambient condition with minimal or no sample preparation. One of the major advantages of LTP MS is selective analysis of low-molecular weight, volatile and low- to medium-polarity analytes in a sample. On the contrary, the selectivity for particular class of compound also implies its limitation in general analysis. One of the critical factors limiting LTP ionization efficiency is poor desorption of analytes with low volatility. In this study, a home-built LTP ionization source with Peltier heating sample stage was constructed to enhance desorption and ionization efficiencies of analytes in a sample and its performance was evaluated using standard mixture containing fatty acid ethyl esters (FAEEs). It was also used to reproduce the previous bacterial identification experiment using pattern-recognition for FAEEs. Our result indicates, however, that the bacterial differentiation from FAEE pattern recognition using LTP ionization MS still has many limitations.

• 대한화학회지
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• 제40권4호
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• pp.235-242
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• 1996

기체 크로마토그래피와 쉽게 연결할 수 있는 Surfatron형의 MIP(Microwave Induced Plasma)용 cavity를 제작하고 헬륨, 아르곤, 질소 등을 플라스마 가스로 사용하여 플라스마를 생성시키고 스펙트럼을 비교하였다. 또한 헬륨과 아르곤, 질소에 미량의 CO2를 혼합하여 각 기체의 스펙트럼을 비교 분석하였으며, 제작한 MIP cavity가 질량분석기와 연결되었을 때 분자이온을 생성시킬 수 있는 이온원으로서의 가능성을 연구하였다. 헬륨과 아르곤 MIP는 높은 준안정 준위의 에너지를 가지기 때문에 분자들이 거의 다 깨어지므로 분자상태로 시료기체의 검출은 거의 불가능하였다. 그러나 질소는 다른 비활성기체에 비하여 낮은 준안정 준위의 어네지를 가지므로 검출하려는 기체성분이 상당부분 분자상태로 존재함을 알 수 있었다.

• 천문학논총
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• 제30권2호
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• pp.559-563
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• 2015

Monitor of All-sky X-ray Image (MAXI) is a Japanese X-ray all-sky surveyer mounted on the International Space Station (ISS). It has been scanning the whole sky since 2009 during every 92-minute ISS rotation. X-ray transients are quickly found by the real-time nova-search program. As a result, MAXI has issued 133 Astronomer's Telegrams and 44 Gamma-ray burst Coordinated Networks so far. MAXI has discovered six new black holes (BH) in 4.5 years. Long-term behaviors of the MAXI BHs can be classified into two types by their outbursts; a fast-rise exponential-decay type and a fast-rise flat-top one. The slit camera is suitable for accumulating data over a long time. MAXI issued a 37-month catalog containing 500 sources above a ~0.6 mCrab detection limit at 4-10 keV in the region ${\mid}{b}{\mid}$ > $10^{\circ}$. The SSC instrument utilizing an X-ray CCD has detected diffuse soft X-rays extending over a large solid angle, such as the Cygnus super bubble. MAXI/SSC has also detcted a Ne emission line from the rapid soft X-ray nova MAXI J0158-744. The overall shapes of outbursts in Be X-ray binaries (BeXRB) are precisely observed with MAXI/GSC. BeXRB have two kinds of outbursts, a normal outburst and a giant one. The peak dates of the subsequent giant outbursts of A0535+26 repeated with a different period than the orbital one. The Be stellar disk is considered to either have a precession motion or a distorted shape. The long-term behaviors of low-mass X-ray binaries (LMXB) containing weakly magnetized neutron stars are investigated. Transient LMXBs (Aql X-1 and 4U 1608-52) repeated outbursts every 200-1000 days, which is understood by the limit-cycle of hydrogen ionization states in the outer accretion disk. A third state (very dim state) in Aql X-1 and 4U 1608-52 was interpreted as the propeller effect in the unified picture of LMXB. Cir X-1 is a peculiar source in the sense that its long-term behavior is not like typical LMXBs. The luminosity sometimes decreases suddenly at periastron. It might be explained by the stripping of the outer accretion disk by a clumpy stellar wind. MAXI observed 64 large flares from 22 active stars (RS CVns, dMe stars, Argol types, young stellar objects) over 4 years. The total energies are $10^{34}-10^{36}$ erg $s^{-1}$. Since MAXI can measure the spectrum (temperature and emission measure), we can estimate the size of the plasma and the magnetic fields. The size sometimes exceeds the size of the star. The magnetic field is in the range of 10-100 gauss, which is a typical value for solar flares.