title: One step 'dip' and 'use' Ag nanostructured thin films for ultrahigh sensitive SERS Detection.
abstract: A simple one step galvanic displacement method which involves dipping of the silicon substrate in the AgNO3/HF solution and using it for SERS application without any further process is demonstrated. The size and shape of the Ag nanoparticles changes as the deposition time is increased. Initially the shape of the particles was nearly spherical and as it grows, becomes oblong and then coalesce to form a discontinuous film with vertically grown hierarchical Ag nanostructures. The sizes of the deposited particles were in the ranges from 30nm to a discontinuous film. It also demonstrated a highly sensitive chemical detection by surface-enhanced Raman scattering of rhodamine 6G dye, down to 10(-16)M concentration. Prepared samples were able to detect lower concentrations of Melamine. Discontinuous thin films with hierarchical Ag nanostructures were obtained for 5min Ag deposition. The formation of Hot spots between the discontinuous islands and also along the hierarchical structures is responsible for the high SERS enhancement. This simple one step, fast, non-lithographic and cost effective method can be applied for various label free detection of analytes of importance.
authors: Advanced Materials and Devices Lab, Department of Physics, Bharathiar University, Coimbatore 641046, Tamil Nadu, India.
authors: Kanakaraj
authors: K
authors: Rajkumar
authors: Department of Nanoscience and Technology, Bharathiar University, Coimbatore 641046, Tamil Nadu, India.
authors: Naidu Dhanpal
authors: ND
authors: Jayram
authors: Department of Nanoscience and Technology, Bharathiar University, Coimbatore 641046, Tamil Nadu, India.
authors: Devanesan
authors: D
authors: Mangalaraj
authors: Department of Nanoscience and Technology, Bharathiar University, Coimbatore 641046, Tamil Nadu, India. Electronic address: rtrkumar@buc.edu.in.
authors: Ramasamy Thangavelu
authors: RT
authors: Rajendra Kumar
mesh_terms: D008567:Membranes, Artificial; D053768:Metal Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure; D012834:Silver / Q000737:chemistry*; D013059:Spectrum Analysis, Raman / Q000379:methods
chemical_list: D008567:Membranes, Artificial; D012834:Silver
keywords: Ag nanostructures; Galvanic displacement reaction (GDR); Hot spots; Surface enhanced Raman scattering (SERS)