2001 Fiscal Year Final Research Report Summary
Measurement of very small quantity of pollutants using laser absorption spectroscopy method
| Project/Area Number |
12650414
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Measurement engineering
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| Research Institution | Hokkaido University |
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Principal Investigator |
BRATESCU Maria A. Hokkaido Univ. Grad. School of Eng., Inst., 大学院・工学研究科, 助手 (70312379)
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| Co-Investigator(Kenkyū-buntansha) |
SUDA Yoshiyuki Hokkaido Univ. Grad. School of Eng., Inst., 大学院・工学研究科, 助手 (70301942)
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| Project Period (FY) |
2000 – 2001
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| Keywords | Laser spectroscopy / Evanescent Wave / Detection Limit / Laser Ablation / Excited Particles / Density / Plasma Diagnostics |
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| Research Abstract |
The main results of the research were focused on the followings objectives : to realize the detection of an established impurity - N, O, C - in plasma. The level of the impurity was ppm. This means to detect about 10^7 cm^<-3> excited atoms from a total excited atom of 〜 10^<13> cm^<-3> ; to obtain a detection S/N value of 〜 10^6 ; to extend the detection limit of different pollutants elements or molecules to ppb (part per billion) range.
We measured Xe(1s_5) density on the discharge tube wall in a layer of 300 nanometers by evanescent wave (EW) laser spectroscopy. We realized a simple and new EW absorption spectroscopy method based on laser collisionally induced fluorescence (LCIF), i.e. the total changes in the emission properties of the gas discharge causes by illumination with radiation having a wavelength corresponding to an atomic transition. As a result of such simple detection system, without spectrograph, the obtained signal to noise (S/N) ratio is about 10^2.
Using laser absorption spectroscopy we measured spatial and temporal density distributions of carbon atoms and argon ions in a laser ablation plume. We measured spatial and temporal density distributions of electron density following the Stark broadening effect on the absorption line.
Using a high voltage transistor GHTS switch we produced a discharge at high pressure and high population excited atoms density, necessary in analytical spectroscopy. Pulsed plasma and laser ablation plasma are used in analytical chemistry.
In our experiment we measured carbon atoms in laser ablation plume and we determined the signal to noise ratio (S/N) of the detection. S/N was about 10^3. To test the performances of the detection system we measured the number density of the ion (argon). Argon ion detection was done with a S/N about 10^2. Carbon detection is important when decomposition of carbon oxides takes place.
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Research Products
(34 results)
