Production of nanostructures on bulk metal samples by laser ablation for fabrication of low-reflective surfaces

• Published in: Applied physics. A, Materials science & processing Vol. 113; no. 2; pp. 291 - 296
• Main Authors: Hopp, Béla, Smausz, Tomi, Csizmadia, Tamás, Vass, Csaba, Tápai, Csaba, Kiss, Bálint, Ehrhardt, Martin, Lorenz, Pierre, Zimmer, Klaus
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.11.2013; Springer
• Subjects: Biological and medical applications; Characterization and Evaluation of Materials; Condensed Matter Physics; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Fundamental areas of phenomenology (including applications); Gold; Industrial applications; Laser deposition; Machines; Manufacturing; Materials science; Methods of deposition of films and coatings; film growth and epitaxy; Nanoscale materials and structures: fabrication and characterization; Nanotechnology; Optical and Electronic Materials; Optics; Other topics in nanoscale materials and structures; Physics; Physics and Astronomy; Processes; Rapid Communication; Surfaces and Interfaces; Thin Films; Ablation Plume; Copper Foam; Pulse Number; Gold Sample; Laser Fluence; Radiation effects; Gold; Laser assisted processing; Pulsed laser deposition; Nanostructures; Laser beam applications; Reflectivity; Near infrared radiation; Silver; Strong correlation; Displacement rates; Laser ablation technique; Copper; Microstructure
• ISSN: 0947-8396; 1432-0630
• DOI: 10.1007/s00339-013-7913-y

Nanostructure formation on bulk noble metals (copper, gold and silver) by a femtosecond laser was studied aiming at the production of low-reflectivity surfaces. The target surface was irradiated with the beam of a 775 nm wavelength and 150 fs pulse duration Ti:sapphire laser. The fluence was in the 16–2000 mJ/cm 2 range, while the average pulse number was varied between 10 and 1000 depending on the scanning speed of the sample stage. The reflectivity of the treated surfaces was measured with a visible–near-infrared microspectrometer in the 450–800 nm range, while the morphology was studied with a scanning electron microscope. A strong correlation was found between the decreasing reflectivity and the nanostructure formation on the irradiated surface; however, the morphology of silver significantly differed from those of copper and gold. For the two latter metals a dense coral-like structure was found probably as a result of cluster condensation in the ablation plume followed by diffusion-limited aggregation. In the case of silver the surface was covered by nanodroplets, which formation was probably influenced by the ‘spitting’ caused by ambient oxygen absorption in the molten silver followed by its fast release during the resolidification.