Laser-induced breakdown spectroscopy of Br and I molecules with alkali-earth elements

In general, bromine and iodine do not produce atomic or ionic emission lines of sufficient intensity to permit their sensitive detection by laser-induced breakdown spectroscopy in air. This situation is mainly due to both their high excitation levels and the position of their strongest emission lines being either in the VUV or NIR range. However, these two elements recombine with alkali-earth elements Ca and Ba to form molecules with intense and characteristic molecular bands that emit in the visible range. Such molecular detection represents a complementary method for LIBS analytical detection of Br and I, which has not been used before. In this paper, we aim to show that these broad emission molecular bands may be useful for many analytical tasks, as these reactions also occur with other halogens, such as F and Cl.