Influence of target temperature on femtosecond laser-ablated brass plasma spectroscopy

Spectral intensity, electron temperature and density of laser-induced plasma (LIP) are important parameters for affecting sensitivity of laser-induced breakdown spectroscopy (LIBS). Increasing target temperature is an easy and feasible method to improve the sensitivity. In this paper, a brass target in a temperature range from 25 °C to 200 °C was ablated to generate the LIP using femtosecond pulse. Time-resolved spectral emission of the femtosecond LIBS was measured under different target temperatures. The results showed that, compared with the experimental condition of 25 °C, the spectral intensity of the femtosecond LIP was enhanced with more temperature target. In addition, the electron temperature and density were calculated by Boltzmann equation and Stark broadening, indicating that the changes in the electron temperature and density of femtosecond LIP with the increase of the target temperature were different from each other. By increasing the target temperature, the electron temperature increased while the electron density decreased. Therefore, in femtosecond LIBS, a hightemperature and low-density plasma with high emission can be generated by increasing the target temperature. The increase in the target temperature can improve the resolution and sensitivity of femtosecond LIBS.