Quartz Crystal Microbalances for quantitative picosecond laser-material-interaction investigations – Part I: Technical considerations

In this work the technical suitability of Quartz Crystal Microbalances (QMBs) for in situ, pulse resolved mass removal measurements is demonstrated for picosecond laser ablation of magnetron sputtered coatings. The QMBs show a linear characteristic of the sensitivity for layer thickness of different metals up to several microns. Laser pulse resolved measurements of the mass ablated from the metal layer were performed. About 400ng of chromium was ablated during the first laser pulse while in subsequent pulses <220ng were removed. This is compared with previous findings. The sensitivity for ablation of the QMBs is found to be larger than for deposition, which is explained by the radial sensitivity of the QMBs. Future refinements of the setup and the benefits of the pulse resolved mass loss measurements for laser based methods like LIBS and LIAS are discussed and will be presented in part II currently in preparation.