TEA CO2 Laser - Polymethyl Methacrylate Interaction: LIBS Hydrogen Analysis

The interaction of a Transversely Excited Atmospheric (TEA) CO2 laser with a polymer polymethyl methacrylate (PMMA) sample in a vacuum ambiance was studied. The main goal was to demonstrate the feasibility of laser-induced breakdown spectroscopy (LIBS) to detect hydrogen. The generation of plasma over the PMMA surface, using a low laser intensity of similar to 48 MW/cm(2) and fluence of similar to 16.5 J/cm(2), required the application of a metal sub-target. Besides hydrogen, the recorded spectra were dominated by atomic lines of carbon and oxygen and band emission of the C-2 and CN molecules. The electron number density and temperature (ionic, vibrational, and rotational) were evaluated to characterize the laser-induced plasma. In addition, PMMA micro-damages (diameter similar to 45 mu m) created by a multipulse laser ablation could find potential applications in sensor technologies.