Hong-Tao Sun, Beibei Xu, Tetsu Yonezawa, Yoshio Sakka, Naoto Shirahata, Minoru Fujii, Jianrong Qiu, Hong Gao
Bi5(GaCl4)3 sample has been synthesized through the oxidation of Bi metal by gallium chloride salt. Powder X-ray diffraction as well as micro-Raman scattering results revealed that, in addition to crystalline Bi5(GaCl4)3 in the product, amorphous phase containing [GaCl4]- and [Ga2Cl7]- units also exist. The thorough comparison of steady-state and time-resolved photoluminescent behaviors between Bi5(GaCl4)3 product and Bi5(AlCl4)3 crystal leads us to conclude that Bi53+ is the dominant emitter in the product, which gives rise to the ultrabroad NIR emission ranging from 1 to 2.7 \mum. Detailed quantum chemistry calculation helps us assign the observed excitations to some electronic transitions of Bi53+ polycation, especially at shorter wavelengths. It is believed that our work shown here not only is helpful to solve the confusions on the luminescent origin of bismuth in other material systems, but also serves to develop novel broadband tunable laser materials.
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http://arxiv.org/abs/1205.6889
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