• Bulletin of the Korean Chemical Society
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• 제18권7호
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• pp.706-710
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• 1997

Isotope ratios of K, Ca, Cr and Fe are measured at cool plasma condition generated using high carrier flow rate and relatively low RF power of 900 W. Background molecular ions are suppressed to below 100 counts which give isobaric interference to the analytes. The background ions show different attenuation characteristics at increased carrier flow rate and hence for each element different carrier flow rate should be used to measure isotope ratios without isobaric interference. Isotope ratios are measured at both scan and peak-hopping modes and compared with certified or accepted ratios. The measured isotope ratios show some mass discrimination against low mass due to low ion energy induced from a copper shield to eliminate capacitive coupling of plasma with load coil.

• Nuclear Engineering and Technology
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• 제50권1호
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• pp.140-144
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• 2018

Isotopic analyses of plutonium and low-enriched uranium mixtures with particle sizes of $0.6-3.3{\mu}m$ were performed using thermal ionization mass spectrometry with a continuous heating method to verify its effectiveness for the accurate analysis of minor isotopes without sample pretreatment. The mixed particles used in this study were prepared from a mixed solution of plutonium (SRM 947) and uranium (U010, $^{235}U$ 1% enriched) reference materials. The isotope ratios for plutonium in the individual mixed particles, including $^{238}Pu/^{239}Pu$, $^{241}Pu/^{239}Pu$ as well as $^{240}Pu/^{239}Pu$, and $^{242}Pu/^{239}Pu$, were in good agreement with the certified values despite the isobaric interference of $^{238}U$ and $^{241}Am$. The isotope ratios for uranium in the mixed particles also agreed well with the certified values within the range of error. However, the isotope ratios for minor isotopes, such as $^{234}U$ and $^{236}U$, in the particles with diameters of less than approximately $1.8{\mu}m$ could not be measured because numbers of $^{234}U$ and $^{236}U$ atoms in analyzed particles are too low. These results indicate that thermal ionization mass spectrometry with a continuous heating method is applicable for the analysis of trace amounts of plutonium isotopes, including $^{238}Pu$ and $^{241}Pu$, despite the presence of the respective isobars $^{238}U$ and $^{241}Am$ in the microsamples.

• Bulletin of the Korean Chemical Society
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• 제22권2호
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• pp.205-209
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• 2001

Uniformly-doped silicon thin films were fabricated by ion beam sputter deposition. The thin films had four levels of copper dopant concentration ranging between 1 ${\times}$1019 and 1 ${\times}$ 1021 atoms/cm3 . Concentrations of Copper dopants were determined by the isotope dilution inductively coupled plasma mass spectrometry (ICP-MS) to provide certified reference data for the quantitative surface analysis by secondary ion mass spectrometry (SIMS). The copper-doped thin films were dissolved in a mixture of 1 M HF and 3 M HNO3 spiked with appropriate amounts of 65 Cu. For an accurate isotope ratio determination, both the detector dead time and the mass discrimination were appropriately corrected and isobaric interference from SiAr molecular ions was avoided by a careful sample pretreatment. An analyte recovery efficiency was obtained for the Cu spiked samples to evaluate accuracy of the method. Uncertainty of the determined copper concentrations, estimated following the EURACHEM Guide, was less than 4%, and detection limit of this method was 5.58 ${\times}$ 1016 atoms/cm3.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
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• pp.243-244
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• 2013

Over the past 15 years, several groups have incorporated radio-frequency quadrupole (RFQ) based instruments before the accelerator in accelerator mass spectrometry (AMS) systems for ion-gas interactions at low kinetic energy (＜40 eV). Most AMS systems arebased on a tandem accelerator, which requires negative ions at injection. Typically, AMS sensitivity abundance ratios for radioactive-to-stable isotope are limited to Xr/Xs ＞10^-15, and the range of isotopes that can be analyzed is limited because of theneed to produce rather large negative ion beams and the presence of atomic isobaric interferences after stripping. The potential of using low-kinetic energy ion-gas interactions for isobar suppression before the accelerator has been demonstrated for several negative ion isobar systems with a prototype RFQ system incorporated into the AMS system at IsoTrace Laboratory, Canada (Ontario, Toronto). Requisite for any such RFQ system applied to very rare isotope analysis is large transmission of the analyte ion. This requires proper phase-space matching between the RFQ acceptance and the ion beam phase space (e.g. 35 keV, ${\varphi}3mm$, +-35 mrad), and the ability to control the average ion energy during interactions with the gas. A segmented RFQ instrument is currently being designed at Korea Institute for Science and Technology (한국과학기술연구원, KIST). It will consist of: a) an initial static voltage electrode deceleration region, to lower the ion energy from 35 keV down to ＜40 eV at injection into the first RFQ segment; b) the segmented quadrupole ion-gas interaction region; c) a static voltage electrode re-acceleration region for ion injection into a tandem accelerator. Design considerations and modeling will be discussed. This system should greatly lower the detection limits of the 6 MV AMS system currently being commissioned at KIST. As an example, current detection sensitivity of 41Ca/Ca is limited to the order of 10^-15 while the 41Ca/Ca abundance in modern samples is typically 41Ca/Ca~10^-14 - 10^-15. The major atomic isobaric interference in AMS is 41K. Proof-of-principal work at IsoTrace Lab. has demonstrated that a properly designed system can achieve a relative suppression of KF3-/41CaF3- ＞4 orders of magnitude while maintaining very high transmission of the 41CaF3- ion. This would lower the 41Ca detection limits of the KIST AMS system to at least 41Ca/Ca~10^-19. As Ca is found in bones and shells, this would potentially allow direct dating of valuable anthropological archives and archives relevant to our understanding of the most pronounced climate change events over the past million years that cannot be directly dated with the presently accessible isotopes.

• 분석과학
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• 제13권3호
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• pp.297-303
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• 2000

저니토 시료 중의 미량 Cd, Cu, Pb, Ni, Zn 등의 분석을 위해 동위원소희석 질량분석법을 이용하였다. 시료는 마이크로파 혼합산(질산, 불산, 과염소산) 분해법을 이용하여 용해하였다. Ammonium pyrrolidenedithiocarbamate(APDC) 용매 추출법을 이용하여 알칼리 및 알칼리 토금속을 분리한 다음 Pb를 측정하고, 나머지 원소들은 이 용액에 $NH_4OH$ 첨가 후 원심 분리하여 Fe, Sn, Ti 등을 제거한 다음 측정하였다. 측정원소의 회수율은 다소 떨어지나 동중원소 방해를 일으키는 매질원소를 효율적으로 제거할 수 있었다. 2종의 저니토 인증표준물질 중의 미량원소 분석에 이 방법을 적용한 결과 인증값과 잘 일치하는 측정 결과를 얻을 수 있었다.

• 분석과학
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• 제29권4호
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• pp.170-178
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• 2016

팔중극자 반응셀을 장착한 사중극자 유도결합플라즈마 질량분광기에서 동위원소 희석법을 사용하여 셀레늄을 분석할 때에 여러 다른 스파이크 동위원소들 ⁷⁶Se, ⁷⁷Se, 및 ⁷⁸Se에 대한 정확도와 정밀도를 비교하였다. 무기 셀레늄 표준용액에 대한 분석결과, ID분석법의 정확도는 매일의 결과는 물론 장기간(세 달간)에도 세 개의 스파이크 모두 1 % 이내의 오차만을 보여주었고 %RSD도 1 % 수준이었다. 동위원소 스파이크 ⁷⁶Se, ⁷⁷Se 은 그 결과값은 비슷하며 ⁷⁸Se이 조금 더 나은 결과를 보여주었다. 하지만 실제시료인 기준물질 NIST SRM 1568a(쌀분말)과 NIST SRM 2967(홍합)에서는 사용하는 스파이크 동위원소에 따라 서로 다른 정확도와 정밀도를 보여주는데 가장 큰 이유는 측정 및 계산에 사용된 m/z에 대한 서로 다른 여러 간섭 때문으로 나타났다. ORC사용으로 인한 SeH의 생성때문에 나타나는 간섭을 보정한 뒤 매트릭스에 포함된 Br, As에 의한 간섭에 대한 보정을 하였다. 결과, 비교적 간단한 매트릭스를 가진 쌀분말일 때 ⁷⁶Se, ⁷⁷Se, 및 ⁷⁸Se은 서로 비슷한 결과를 얻었으며 각 각 80% 정도의 회수율을 꾸준하게 보여주었다. 정밀도는 ⁷⁸Se의 경우에는 1.8% RSD로서 무기표준물의 경우와 비슷하다. ⁷⁶Se와 ⁷⁷Se는 각 각 8.6%, 6.3% RSD로서 약간 높지만 전체적으로 이 실험은 신뢰할 수 있다고 보인다. 매트릭스가 복잡한 홍합의 경우에도 ⁷⁶Se와 ⁷⁷Se는 오차가 5 % 이내로서 정확한 결과를 보여주나 정밀도는 RSD 15 % 수준으로 조금 높은 편이다. 하지만 ⁷⁸Se의 경우에는 정확도도 나쁘지만 정밀도가 매우 나빠서(100% 이상의 RSD) 신뢰할 수 없는 결과를 보여준다. 이 는 ⁷⁸Se의 경우, 워낙 Br의 간섭이 크기 때문으로 비록 수학적 보정을 한다하여도 충분하지 않음을 보여준다. 따라서 스파이크 동위원소를 선택할 때에는 매트릭스가 간단하다면 신호가 높은 ⁷⁸Se동위원소를 선택하는 것이 조금 더 유리할 수 있지만 Br이나 간섭이 많을 때는 ⁷⁸Se은 피하고 ⁷⁶Se이나 ⁷⁷Se을 선택하여야 하며 이 경우 충분히 좋은 결과를 보여줄 수 있다.