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Semi-Quantitative Determination of Main Components of Soils and Rocks by CF-LIBSтезисы доклада
- Авторы: Popov A.M., Labutin T.A., Zaytsev S.M., Shestakov I.A., Zorov N.B., Kalko I.A.
- Сборник: Book of Abstracts EMSLIBS 2013 Bari (Italy) September 16-20, 2013
- Серия: Euro-Mediterranean Symposium on Laser Induced Breakdown Spectroscopy
- Том: 7
- Тезисы
- Год издания: 2013
- Место издания: University of Bari Bari, Italy
- Первая страница: 187
- Последняя страница: 187
- Аннотация: Nowadays Laser-induced breakdown spectrometry (LIBS) is widely used for direct quantitative analysis of various environmental or geological samples, such as sands, soils, glasses, rocks, etc. However, the reference samples are usually required to construct calibration curve due to matrix effects. In this work, we applied calibration-free procedure (CF) to determine the main components (K, Na, Si, C, Ca, Mg, Fe, Al, Ti, O) of soils and rocks without reference materials. Several reference materials of soils (NIST, BAM and Russian CRM’s) and ICP-AES certified geological samples (copper-porphyries) were analysed by CF-LIBS. To examine local thermodynamic equilibrium (LTE) plasma temperature and electron density were estimated. Studying by plasma evolution, LTE window was found between 2 μs and 7-9 μs depending on samples. To reduce spectral ranges used for CF-LIBS analysis we have used the only one line for each element. The absence of self-absorption was checked for the each line by curves-of-growth method. For example, weak ionic line at 413.089 nm was chosen for silicon determination. On the contrary, we have not used the spectral lines of oxygen to determine its content. For simplicity, we assumed that the oxygen was mainly presented in soils and rocks as the highest oxides of elements, such as the SiO2, CO2, Al2O3, TiO2, Fe2O3 etc. Abundance ratios of neutral and singly- and doublyionized species of each component were calculated by recurrent Saha equations combined with the equation of conservation of mass and the lowering factors of ionization potential. As a result, the proposed technique for determination of components without reference samples was suitable for semi-quantitative analysis of main components (Si, Fe, Al, Ca, Ti, Mg, Na, and K with accuracy error from -5% to + 10%). The strong deviation in carbon content (more than 50%) was obtained for carbon-reach soils due to organic substances such as humic acids etc.
- Добавил в систему: Лабутин Тимур Александрович