Identification of atomic lines and molecular bands of benzene and carbon disulfide liquids by using LIBS

Abstract

Plasma emission of liquid benzene (C6H6) and carbon disulfide (CS2) have been studied by using the laser-induced breakdown spectroscopy (LIBS) technique in air. Atomic lines of carbon, hydrogen, sulfur, nitrogen, and oxygen and molecular emissions of CN and C2 have been identified. The formation mechanism of C2 and CN molecules has been discussed. The combustion process and high mole fraction of hydrogen in benzene caused a decreasing atomic line intensity of oxygen and an increasing atomic line intensity of hydrogen with respect to the CS2 and air. Additionally, more intense CN molecular bands and weak nitrogen atomic lines in the C6H6 spectrum compared to CS2 have been observed. Furthermore, molecular emissions of C2 have not been observed in the CS2 spectrum. The electron temperature and vibrational temperature have been calculated from the atomic lines and molecular band intensity, respectively. Finally, the validity of the local thermodynamic equilibrium (LTE) assumption in this experiment has been shown.