Solange Muralha

The main purpose of this work was to study the surface topography of bovine femoral bone treated with a femtosecond infrared laser and the changes in the bone structure and composition induced by laser ablation. The laser treatments were carried out using a Yb:KYW chirped-pulse-regenerative amplification laser with a pulse duration of about 500 fs, a wavelength of 1030 nm and fluences ranging from 0.55 to 1.09 J/cm2. The ablation process was monitored in real time by acoustic emission measurements. The surfaces resulting from the laser ablation experiments were studied by scanning electron microscopy (SEM), glancing incidence X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR) and µRaman Spectroscopy. Acoustic emission measurements revealed two different ablation regimes associated to optical penetration depth ablation and electron thermal diffusion ablation, respectively. The laser treated surfaces are free of melting, cracks and redeposited debris. A slight decrease on the bone organic material content was observed in the FTIR, µRaman and XPS spectra, as well as a partial recrystallization of hydroxyapatite, detected by X-ray diffraction.