  Bi5(GaCl4)3 sample has been synthesized through the oxidation of Bi metal by
gallium chloride (GaCl3) 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 emission ranging from 1 to 2.7 micrometer. 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.
