Investigation on the effects of laser parameters on the plasma profile of copper using picosecond laser induced plasma spectroscopy

Laser induced plasma generation and characterization, affected by laser parameters and sample physical properties, represent important phenomena in many fields of applications. In this work, we present new studies on the effects of an appropriate combination of laser wavelengths and pulse energies on the generated plasma characterization using a single shot picosecond Nd:YAG laser. The plasma plume of a pure copper sample has been generated by laser induced plasma spectroscopy (LIPS) using a single shot 170 ps laser pulse with wavelengths (266, 355, 532 and 1064 nm) and varying laser fluence (10-41 J/cm(2)). The spectral intensities of Cu I 324.75, 327.39, 515.32 and 521.82 nm have been observed. The plasma electron temperature and density have been determined from the Boltzmann plots and Stark-broadening profiles of the plasma spectral lines, respectively, assuming the local thermodynamic equilibrium (LTE) condition. It has been found that the electron temperature and electron density values increase from around 10,000 to 20,000 K and around 2 x 10(17) to 1.5 x 10(18) cm(-3), respectively, with the increase in the laser wavelength and pulse fluence gradually. These observations can be understood due to the variations of mass-ablation rates, inverse-Bremsstrahlung, and photo-ionization with the studied pulse wavelength and pulse energy. The obtained results explore the opportunity to control specific generated plasma parameters by applying proper picosecond pulse parameters which can be considered in many fields of material science spectroscopic analysis and control the plasma interaction dynamics.