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( L Zhang ),( K Wagatsuma ) 경남대학교 신소재연구소 2013 신소재연구 Vol.25 No.-
Laser-induced plasma - atomic emission spectrometry (LIPS) is a rapid analytical method which can determine the elemental composition in a remote-sensing configuration without any need for sample pretreatment; therefore, it is expected to be employed for the practical analysis of industrial process control. More recently, recycling of metallic materials can greatly contribute to the saving of resources as well as energy, because the amounts of metal products are huge and they contain various rare metals such as nickel and chromium. In the recycling process, an on-site analytical method would give useful information for separating the steel products by employing the quantitative analytical result. In laser-induced plasma (LIP), a gas body in the plasma state, in which specimen sampling, atomization, and ionization occur, is produced near the sample surface through convergent laser beam irradiation with a high energy density. This sampling process is called laser ablation, where sample atoms are evaporated from the surface and are then introduced into the plasma. The pulsated LIP has both spatial and temporal variations, depending on various experimental parameters, such as the kind and pressure of the plasma gas employed, which is generally known as an expansion process of the plasma [1]. It means that the emission zone changes with the progress of the plasma to produce a plume-like shape, which is strongly dependent on the nature of the plasma gas. Therefore, time-resolved measurements of the emission spectra give useful information on optimization of the measuring conditions for the emission analysis, such as the delay time as well as the gate width on the data acquisition; however, such measurements cannot provide the overall variation of the plasma expansion. For this purpose, a two-dimensional image of a spectral line emitted from LIP should be observed, which is expected to give information on the fundamental processes occurring in the LIP. In the present work [2], we focused on the determination of copper in steel samples, because it is a typical tramp element containing in steel scraps. For this purpose, the intensity variations of iron emission lines as well as copper atomic lines were investigated in various experimental conditions in LIPS, in order to obtain the optimum operating parameters for the laser as well as the detection system, when argon was selected as the plasma gas. Several pairs of iron and copper emission lines were tested to improve the performance of the calibration curve. [1] Y. Ushirozawa, K. Wagatsuma: Anal. Sci., 2006, 22, 1011. [2] L. Zhang, K. Wagatsuma: ISIJ International, 2013, 54(12), in press.