Femtosecond pulsed laser deposition of biological and biocompatible thin layers

• Published in: Applied surface science Vol. 253; no. 19; pp. 7806 - 7809
• Main Authors: Hopp, B., Smausz, T., Kecskeméti, G., Klini, A., Bor, Zs
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Amsterdam Elsevier B.V 31.07.2007; Elsevier Science
• Subjects: AFM; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; FTIR; Physics; PLD, Thin films; AFM; FTIR; PLD, Thin films; Thin films; Atomic force microscopy; Fourier transform spectra; Pulsed laser deposition; Infrared spectra; AFM; FTIR; PLD; Film growth
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2007.02.102

In our study we investigate and report the femtosecond pulsed laser deposition of biological and biocompatible materials. Teflon, polyhydroxybutyrate, polyglycolic-acid, pepsin and tooth in the form of pressed pellets were used as target materials. Thin layers were deposited using pulses from a femtosecond KrF excimer laser system (FWHM = 450 fs, λ = 248 nm, f = 10 Hz) at different fluences: 0.6, 0.9, 1.6, 2.2, 2.8 and 3.5 J/cm 2, respectively. Potassium bromide were used as substrates for diagnostic measurements of the films on a FTIR spectrometer. The pressure in the PLD chamber was 1 × 10 −3 Pa, and in the case of tooth and Teflon the substrates were heated at 250 °C. Under the optimized conditions the chemical structure of the deposited materials seemed to be largely preserved as evidenced by the corresponding IR spectra. The polyglycolic-acid films showed new spectral features indicating considerable morphological changes during PLD. Surface structure and thickness of the layers deposited on Si substrates were examined by an atomic force microscopy (AFM) and a surface profilometer. An empirical model has been elaborated for the description of the femtosecond PLD process. According to this the laser photons are absorbed in the surface layer of target resulting in chemical dissociation of molecules. The fast decomposition causes explosion-like gas expansion generating recoil forces which can tear off and accelerate solid particles. These grains containing target molecules without any chemical damages are ejected from the target and deposited onto the substrate forming a thin layer.