In this paper, the technique of laser pulse breakdown spectroscopy (LIBS) under the influence of the pulse Nd:YAG laser of 1064nm wavelength and with a pulse time of 10ns was used on different samples of writing ink models. In this work, the de-Broglie wavelength was measured. After calculating the electron temperature and assuming the local thermal equilibrium conditions (LTE), and using a spectral detector model (View spectra 2100) within the spectral range (200nm-900nm), the results after performing the analysis showed differences in the D-Broglie thermal wavelength of the plasma. The formation and temperature of the electron, which can be applied in plasma spectroscopy processes in many sciences, including the field of forensic evidence, to detect forgery in documents and documents.

De-Broglie Thermal Wavelength, LIBS, Electron Temperature, Writing Inks.