Detecting Indium In Electric Waste Using Laser Induced Breakdown Spectroscopy

Our system for time-resolved laser induced fluorescence (TR-LIF) measurement is described in Terzic et al. (2008) and Rabasovic et al. (2009a,b). First published results could be found in Rabasovic et al. (2008). Nd:YaG laser used in our TR-LIF experiments is powerful enough (365 mJ at 1064 nm, variable OPO output >5mJ), so that the system also could be used for laser induced breakdown spectroscopy (LIBS). In this paper, preliminary results regarding testing of LIBS technique for detecting indium in electric waste are presented. Indium is a soft, gray metallic element which belongs to the elements of group III of the Periodic Table. It was found and spectroscopically identified as a minor component in zinc ores. Because of its low melting point, 429.75 K, it is technologically attractive, especially in the semiconductor industry and optoelectronics. Optically transparent electrodes used in liquid crystal displays (LCD) are made of indium tin oxide. However, the uses of indium are rapidly increasing and there are many other electronic devices which contain indium. It is relatively rare and ranks 61st in crustal abundance. It is about three times as abundant as silver. Our results regarding electronic spectroscopy of Indium could be found in Rabasovic et al. (2008, 2009a).