Laser Ablation of Carbon Fiber Reinforced Plastics: Laser-Ionization TOF Mass Spectrometric Study

Neutral fragments from a nanosecond KrF excimer laser-ablated carbon fiber reinforced plastic (CFRP, carbon fiber/epoxy resin composite) were investigated by laser-ionization time-of-flight (TOF) mass spectrometry in order to explore the laser ablation dynamics of CFRP. The neutrals were detected after the post-ionization by an ArF excimer laser pulse at variable delay times, td, relative to the ablation KrF excimer laser pulse. Depending on the ablation fluence, TOF mass spectra and laser-etched surface morphology drastically changed. At the laser fluence of 0.3 J·cm, the resins were preferentially ablated. The TOF mass spectra contained a main peak at 36 amu assigned to C3 in early delay times, and then the main peak changed to 39 amu assigned to C3H3. At 1.0 and 1.5 J·cm, both of carbon fibers and resins were ablated. The most prominent peak was C3 independent of the delay time. The delay-time distribution of C3 exhibited a single peak at 0.3 J·cm and then changed to two peaks at 1.5 J·cm. The fits with shifted Maxwell-Boltzmann distribution gave good agreement, suggesting transient maximum CFRP temperature of 4700, 6400, and 7100 K at 0.3, 1.0 and 1.5 J·cm, respectively.