Influence of target temperature on AlO emission of femtosecond laser-induced Al plasmas

The influence of target temperature on molecular emission of femtosecond laser-induced breakdown spectroscopy (LIBS) was investigated experimentally. An Al target was ablated to produce laser-induced plasma. The Al target was uniformly heated to a maximum of 250 °C. The measured molecular emission was AlO (Δν = 0) from the femtosecond LIBS of the Al target. The measurement indicated that the molecular emission of AlO increased as the temperature of the Al target increased. In addition, a two-temperature model was used to simulate the evolution of electron and lattice temperature of the Al target with different initial temperatures. The simulated results showed that the electron and lattice temperatures of Al irradiated by femtosecond laser increased with increasing the initial temperature of the Al target; also, the simulated ablated depth increased. Therefore, an increase in the initial Al target temperature resulted in an enhancement in the spectral signal of AlO from femtosecond LIBS of Al which was directly related to the increase in the size of the ablated crater. The study suggested that increasing the temperature of the target will improve the intensity of molecular emission in femtosecond LIBS.