Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành hóa học dành cho các bạn yêu hóa học tham khảo đề tài: Characterization of MHz pulse repetition rate femtosecond laser-irradiated gold-coated silicon surfaces | Sivakumar et al. Nanoscale Research Letters 2011 6 78 http content 6 1 78 o Nanoscale Research Letters a SpringerOpen Journal NANO EXPRESS Open Access Characterization of MHz pulse repetition rate femtosecond laser-irradiated gold-coated silicon surfaces Manickam Sivakumar1 3 Krishnan Venkatakrishnan2 Bo Tan1 Abstract In this study MHz pulse repetition rate femtosecond laser-irradiated gold-coated silicon surfaces under ambient condition were characterized by scanning electron microscopy SEM transmission electron microscopy TEM X-ray diffraction analysis XRD and X-ray photoelectron spectroscopy XPS . The radiation fluence used was J cm2 at a pulse repetition rate of 25 MHz with 1 ms interaction time. SEM analysis of the irradiated surfaces showed selfassembled intermingled weblike nanofibrous structure in and around the laser-irradiated spots. Further TEM investigation on this nanostructure revealed that the nanofibrous structure is formed due to aggregation of Au-Si Si nanoparticles. The XRD peaks at and were identified as 200 211 and 321 reflections respectively corresponding to gold silicide. In addition the observed chemical shift of Au 4f and Si 2p lines in XPS spectrum of the irradiated surface illustrated the presence of gold silicide at the irradiated surface. The generation of Si Au-Si alloy fibrous nanoparticles aggregate is explained by the nucleation and subsequent condensation of vapor in the plasma plume during irradiation and expulsion of molten material due to high plasma pressure. Introduction Nanostructures of Au Au-Si alloy and Si have been employed in micro and nanoelectromechanical systems 1 biosensors 2 and photonics 3 4 . The fieldemission property 5 of Au-Si alloy structures is used for the fabrication of panels and displays. Au-Si alloy nanoparticles are increasingly relevant as they are used as catalysts in the growth of nanowires 6 . Recently femtosecond lasers have proven to be a powerful tool