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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: Synthesis of Nanoscale Tips Using Femtosecond Laser Radiation under Ambient Condition | Nanoscale Res Lett 2010 5 438-441 DOI 10.1007 S11671-009-9502-8 NANO EXPRESS Synthesis of Nanoscale Tips Using Femtosecond Laser Radiation under Ambient Condition M. Sivakumar K. Venkatakrishnan B. Tan Received 27 October 2009 Accepted 20 November 2009 Published online 29 November 2009 The Author s 2009. This article is published with open access at Springerlink.com Abstract We report a unique growth of platelet-shaped nanoscale tips of transparent dielectric using femtosecond laser radiation at MHz pulse repetition rate with nitrogen background gas flow under ambient condition. The tips grew with sharp nanoscale apex while their base and lengths are of the order of few hundred nanometers. In the absence of nitrogen the irradiation leads to nanofibrous structure formation. The collision between the nitrogen gas atoms and the vapor species slows down plume expansion and lead to an increase of nanoparticles size. This prevents the fibrous structure formation and provides appropriate condition for nanoscale tips growth. Keywords Femtosecond laser ablation Nanoscale tips Nanostructuring Introduction Nanoscale tips wires tubes and rods of semiconductor ceramic and dielectric materials have been investigated for applications such as probes for scanning probe microscopy emitters for field-emission-based devices and solar cells 1 . Also there is a significant amount of ongoing research on selective and sensitive optical nanosensors of biological agents. In this context the current emerging trend in nanoscale research is controlled synthesis with well- M. Sivakumar B. Tan Department of Aerospace Engineering Ryerson University 350 Victoria Street Toronto ON M5B 2K3 Canada K. Venkatakrishnan El Department of Mechanical and Industrial Engineering Ryerson University 350 Victoria Street Toronto ON M5B 2K3 Canada e-mail venkat@ryerson.ca defined sizes and geometries unravelling their fundamental physical properties and assembly of these nanoscale building blocks into functional .
