Volume 4, Issue 6, June 2013

Nano Science And Engineering By Ionizing Radiations

D. K. Avasthi; S. K. Sarkar; A. Tripathi; T. Mukherjee

Advanced Materials Letters, 2013, Volume 4, Issue 6, Pages 385-389
DOI: 10.5185/amlett.2013.6001

The properties of materials at the nano scale critically depend on their size and shape, thus opening a new exciting area of nanotechnology. Its main thrust is to create novel functional materials with their unique physical, chemical and biological properties. The field of engineering of materials with desired properties is seeing a revolution as it becomes feasible to fabricate nanoscale building blocks having precisely controlled size and composition. Ionizing radiation (photon, electron and ion beams) have provided immense possibilities for engineering the desired properties of materials and are now emerging as indispensible tools for mesoscopic structuring [1-5]. The field of materials engineering through nano approach has demonstrated tremendous potential in the development of different types of novel materials with new characteristics and functions. The aim of nano engineering with photon, electron and ion beams is to control the nano scale structure of materials to optimize their properties and functionality.

Stabilization Of FeCo Alloy Phase In FeCo-SiO2 nanocomposites

Hardeep Kumar; L. Olivi;G. Aquilanti; S. Ghosh; P. Srivastava; D. Kabiraj; D. K. Avasthi

Advanced Materials Letters, 2013, Volume 4, Issue 6, Pages 390-397
DOI: 10.5185/amlett.2012.ib.101

A series of FeCo-SiO2 granular films of different FeCo atomic concentration (33-54%) have been prepared by fast atom beam sputtering technique and post-annealed in inert (Ar) and reducing (H2) gas environments. Fe and Co K-edge XANES analysis of as-deposited films indicate that both Fe and Co are present mainly in their elemental (Fe 0 , Co 0 ) state. A partial oxidation of Fe and Co is observed, as the FeCo alloy content decreases (54 to 33%) due to reduced particle size. XANES/XAFS analysis shows the formation of FeCo alloy with bcc Fe structure in H2 environment annealed films. The XRD and Raman analysis of Ar environment annealed films suggest the formation of Co3O4 and CoFe2O4 phases. The Ar environment is found not to be effective reducing medium to stabilize the FeCo alloy phase, while H2 environment annealing (450-700 o C) leads to formation of bcc FeCo alloy. 

Azimuthal Angle Dependence Of Nanoripple Formation On Si(100) By Low Energy Ion Erosion

Sarathlal K.V; ;Ajay Gupta; Satish Potdar; Mohan Gangrade; V. Ganesan; and Ajay Gupta

Advanced Materials Letters, 2013, Volume 4, Issue 6, Pages 398-401
DOI: 10.5185/amlett.2012.ib.102

Generation of self organized nanoripple patterns on Si (100) single crystal surface using low energy Ar ion beam erosion has been studied. Ion energy and ion fluence dependence of the ripple pattern is in general agreement with the reported works. However, it is found that at relatively low fluences, the pattern formation depends upon the direction of the projection of the ion beam on Si surface with respect to its crystallographic orientation. Ripple formation is facilitated if the projection of ion beam on the sample surface is along (010) direction as against (011) direction. For higher ion fluence, when the Si surface layer is fully amorphized, pattern formation is independent of the azimuthal direction of the ion beam.

Low Energy Bombardment Induced Formation Of Ge Nanoparticles

Indra Sulania; Mushahid Husain;D. K. Avasthi; Dinesh Agarwal; Manish Kumar

Advanced Materials Letters, 2013, Volume 4, Issue 6, Pages 402-407
DOI: 10.5185/amlett.2012.ib.103

We present the formation of Ge nanostructures by bombardment of 1.5 keV Ar atoms on Ge (100). The bombardment was carried out at normal incidence with variation in the fluences from 5x10 15 to 3x10 17 atoms/cm 2 . Near surface chemical study on the pristine and irradiated Ge samples has been carried out using X-ray Photoelectron Spectroscopy. In the near surface region of pristine sample, prominence of Ge 4+ was observed by 3d core level present at a binding energy of 33.5 eV. After the irradiation, the evolution of two new core level peaks at binding energies of 29.8 and 30.4 eV confirms the reduction of Ge 4+ to elemental Ge. Atomic Force Micrographs show an increase in surface roughness from 0.4 nm to 10 nm for pristine to sample irradiated at highest fluence. Using the scaling laws and calculating the roughness and growth exponents deduced from Power Spectral Density analysis, it has been found that ion induced coarsening leads to the surface roughening. Further, using the simulation code, it is found that with increasing fluence of bombardment, the deformation of surface starts initially which later on results in simultaneous formation of dots and pits.

Synthesis Of Ag Nanoparticles On Polymer Surface: 150 KeV Ar Ion Irradiation Of Ag-PVC Bilayer

Jai Prakash; A. Tripathi; G. B. V. S. Lakshmi; V. Rigato; Jalaj Tripathi; D. K. Avasthi

Advanced Materials Letters, 2013, Volume 4, Issue 6, Pages 408-412
DOI: 10.5185/amlett.2012.ib.104

Thin metal films of Ag (~10 nm) deposited on spin coated PVC film on quartz substrate, were irradiated with 150 keV Ar ions at fluences varying from 5×10 15 to 5×10 16 ions/cm 2 and characterized with Rutherford backscattering spectrometry (RBS), atomic force microscopy (AFM), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) techniques. RBS spectra show sputtering of the Ag film. As a result of ion irradiation, isolated Ag nanoparticles are formed on the surface. The size and size distribution of Ag nanoparticles are found to be dependent on ion fluence. Contact angle measurements were carried out to study the hydrophilic nature of the surface at varying fluences. Results are explained in the framework of sputtering from the surface due to dense collision cascade resulting from Ar ion and Ag/PVC film interaction.

Synthesis Of Carbon Nanowires By SHI Irradiation Of Fullerene C70 thin Film 

R. Singhal; A. Tripathi; D. K. Avasthi

Advanced Materials Letters, 2013, Volume 4, Issue 6, Pages 413-417
DOI: 10.5185/amlett.2012.ib.105

Electrically conducting carbon nanowires, all parallel to each other and embedded in fullerene C70 matrix are created by swift heavy ion irradiation of thin fullerene C70 film at low fluences (up to 10 10 ions/cm 2 ). The conductivity of the wires is several orders of magnitude higher than the surrounding material and it is due to the transformation of fullerene into amorphous carbon within each ion hit zone. These conducting nanowires are evidenced by conducting atomic force microscopy. The typical diameter of the conducting tracks is observed to be about 11-21 nm.

Stimuli-responsive Membranes Through Graft-copolymerization Of Acrylic Acid (AAc) Onto Polycarbonate Track Etched (PCTE) Membrane

Sunita Rattan; Teena Sehgal

Advanced Materials Letters, 2013, Volume 4, Issue 6, Pages 418-422
DOI: 10.5185/amlett.2012.ib.106

Radiation grafting of the Track Etched Membranes (TEMs) is a versatile tool for the formation of stimulus responsive membranes which change their permeation properties in response to environmental stimuli such as pH or temperature. Stimuli-responsive polymeric membranes have attracted the attention of researcher all around the world owing to their potential applications in the fields of controlled drug delivery, bio separation, water treatment, and chemical sensors. Acrylic acid (AAc), well known for its novel pH-sensitive behavior in aqueous media was successfully grafted on the surface and in the pores of polycarbonate track etched membrane (PCTE). The influence of reaction parameters such as monomer concentration, reaction time, temperature and concentration of the initiator on the grafting yield was investigated in detail. The membranes were characterized through Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM) techniques. The pH-responsive behaviour of the PCTE-g-AAc membranes was studied. The PCTE-g-AAc membranes exhibit fast and reversible response to the environmental pH.

Effect Of Swift Heavy Ion On Structural And Optical Properties Of Undoped And Doped Nanocrystalline Zinc Oxide Films

Vinod Kumar; L. P. Purohit;Fouran Singh; R. G. Singh

Advanced Materials Letters, 2013, Volume 4, Issue 6, Pages 423-427
DOI: 10.5185/amlett.2012.ib.107

Swift heavy ion (SHI) induced modification in structural and optical properties of undoped and doped nanocrystalline (nc) ZnO films deposited by sol-gel method are investigated. These nanocrystalline films were irradiated by MeV ions of Au, Ag and Ni at various ion fluences. The structural properties were studied using X-ray diffraction and it shows that the average crystallite size of ZnO films is observed to increase by the irradiation. The atomic force microscopy (AFM) study of films shows that the roughness of the films varies with increase in the fluence. A maximum transmittance is observed to be 85% in the visible region for doped films. It is also shown that the bandgap of undoped and doped ZnO films is varied using SHI irradiation. The modifications of structural and optical properties are explained in terms of thermal spikes induced by SHIs.

Modification Of Nanocrystalline RF Sputtered Tin Oxide Thin Film Using SHI Irradiation

Vijay Kumara; Anshul Jaina; Deepti Pratapa; D.C. Agarwalb; I. Sulaniab; V. V. Siva Kumarb; A. Tripathib; S. Varmac; R.S. Chauhan

Advanced Materials Letters, 2013, Volume 4, Issue 6, Pages 428-432
DOI: 10.5185/amlett.2012.ib.108

Nano crystalline tin oxide thin films were deposited on Si and quartz substrates using R. F. magnetron sputtering technique. A set of films was annealed in oxygen environment. These as-deposited and annealed films were irradiated using 100 MeV Ag ions at different fluences ranging from 3×10 11 to 3×10 13 ions/cm 2 . The structural, optical and surface morphological properties of films were studied using X-ray diffraction (XRD), UV-Vis spectroscopy, and atomic force microscopy (AFM) techniques. As deposited films showed the polycrystalline nature and annealing enhances the crystallinity along a particular plane. Upon irradiation at lower fluences up to 3×1012 ions/cm 2 , reduction in crystallinity is observed but at highest fluence 1×10 13 ions/cm 2 a small increase in crystallinity occurs as inferred from XRD spectra. UV-Vis study showed red shift at the lower fluences and blue shift at higher fluences. The pristine film, as observed in AFM micrograph, has randomly distributed surface nano structures with broader size distribution. Irradiation induces the formation of regular shape structures with narrow size distribution. These results may be attributed to the energy deposited by swift heavy ions in the film.

Swift Heavy Ion Irradiation Induced Structural, Optical And Conformational Modifications In Conducting Polymer Nanostructures

A. Kumar;Somik Banerjee

Advanced Materials Letters, 2013, Volume 4, Issue 6, Pages 433-437
DOI: 10.5185/amlett.2012.ib.109

Structural and conformational modifications in conducting polymer nanostructures viz., Polyaniline (PAni) nanofibers induced by swift heavy ion (SHI) irradiation have been investigated employing TEM, XRD, UV-Vis, FTIR and micro-Raman spectroscopy. Upon interaction with the highly energetic ions, PAni nanofibers are fragmented and get amorphized. The local range of order is found to decrease with a corresponding increase in the concentration of point defects and dislocations leading to the enhancement in strain. Vibrational spectra of the pristine and SHI irradiated PAni nanofibers studied using FTIR and micro-Raman (μR) spectroscopy indicate conformational changes in PAni nanofibers upon SHI irradiation. Loss of π-stacking due to the enhancement in the torsion angle between Cring-N-Cring upon irradiation is indicative of strong electrostatic interaction between the electron rich C-N site in the aromatic rings of PAni chains and the ion beam. The most significant variation in PAni nanofibers upon SHI irradiation is the transformation of para di-substituted benzene (benzenoid) structure of PAni into the quinone di-imine (quinoid) structures; a phenomenon that has been simultaneously observed in both the FTIR and Raman spectra. The presence of two main peaks representing the same structures in PAni nanofibers in both the Raman and IR spectra is because of the presence of delocalized sp2 phases and local disorder in PAni nanofibers, which gives rise to electrical and mechanical fluctuations that destroy the symmetry rules.

Effect Of Irradiation Of Si5+­ ion On Fe Doped Hydroxyapatite

V. Sarath Chandra; K. Elayaraja; R. V. Suganthi; M. I. Ahymah Joshy; I. Sulania; P.K. Kulriya; K. Asokan; D. Kanjilal; S. Narayana Kalkura

Advanced Materials Letters, 2013, Volume 4, Issue 6, Pages 438-443
DOI: 10.5185/amlett.2012.ib.110

Hydroxyapatite (HAp, Ca10(PO4)6(OH)2) is the main inorganic component of hard tissues like bone and teeth. HAp incorporated with magnetic ions, play an important role in cell separation, magnetic resonance imaging (MRI), targeted drug delivery and in hyperthermia treatment of cancer. In this study, the effect of 60 MeV Si 5+ ion on the hydrothermally synthesized Fe 3+ doped hydroxyapatite (Fe-HAp, 33 nm) was investigated. At higher fluences, partial amorphization with an increase in the cluster size and surface roughness was observed. Depending on the ion fluence, pores ranging from 300 to 360 nm in size were produced. Irradiated Fe-HAp samples showed enhanced haemocompatibility and bioactivity. The drug (amoxycillin, AMX) loaded irradiated samples exhibited high antimicrobial activity.

In-situ TEM Observation Of Electron Irradiation Induced Shape Transition Of Elongated Gold Nanoparticles Embedded In Silica

S. Mohapatra; J. Ghatak;D.K. Avasthi; Y.K. Mishra

Advanced Materials Letters, 2013, Volume 4, Issue 6, Pages 444-448
DOI: 10.5185/amlett.2012.ib.111

Elongated Au nanoparticles (NPs) embedded in silica matrix were fabricated by 100 MeV Ag ion irradiation of 3 MeV Au ion implanted SiO2/Si(100) substrates, annealed at 1050 o C. Electron-beam-induced shape evolution of elongated Au NPs embedded in SiO2 has been studied by high resolution transmission electron microscopy. Electron beam irradiation resulted in a decrease in the aspect ratio of Au NPs from ~ 1.4 to 1 with increase in irradiation time. The observed ellipsoidal-to-spherical shape transition of Au NPs has been ascribed mainly to the cumulative effects of electron beam induced heating, softening of silica matrix and radiation enhanced diffusion of knock-on displaced O and Si atoms, resulting in local stress relaxation.

Shape Evolution Of CdSe Nanomaterials In Microheterogenous Media

Shalini Singh; S. Adhikari;S. K. Sarkar; Apurav Guleria; M. C. Rath; A. K. Singh

Advanced Materials Letters, 2013, Volume 4, Issue 6, Pages 449-453
DOI: 10.5185/amlett.2012.ib.112

Cadmium selenide, CdSe nanomaterials were synthesized in microhetergenous media consisting of water-in-oil type microemulsions using the surfactant, cetyl trimethyl ammonium bromide (CTAB) and cyclohexane as the oil, under two different experimental conditions. In one set of experiments, the synthesis was carried out by normal chemical route at room temperature, named as green chemistry route. In another set, the synthesis was carried out through radiation-chemical route using 7 MeV electron beam using a linear electron accelerator (LINAC). In the previous case, the shape of CdSe nanomaterials was found to evolve from isotropic spherical to anisotropic rod like structures in lower w0 microemulsions with time. Similar observations were obtained in the case of CdSe nanomaterials synthesized via electron beam irradiation. The photoluminescence was found to be different in the CdSe nanomaterials formed by these two different routes. In the former case, the band gap photoluminescence was observed from the immediately produced nanomaterials, however with aging after a day there were two distinct band gap photoluminescence as well as trap state photoluminescence observed at room temperature. On the contrary, in the case of electron beam induced CdSe nanomaterials the trap state photoluminescence was always dominating irrespective of the aging.

Effect Of Electron Beam Irradiation On Photoluminescence Properties Of Thioglycolic Acid (TGA) Capped CdTe Nanoparticles

Chethan Pai S; L. M. Kukreja;Ganesh Sanjeev; M. P. Joshi; S Raj Mohan; T. S. Dhami; Jayakrishna Khatei; K S Koteshwar Rao

Advanced Materials Letters, 2013, Volume 4, Issue 6, Pages 454-457
DOI: 10.5185/amlett.2012.ib.113

Irradiation effects of 8 MeV electrons on photoluminescence properties of thioglycolic acid (TGA) capped CdTe quantum Dots (QD) are presented. Steady-state and time-resolved photoluminescence (PL) spectroscopy were used for anlayzing PL properties of both irradiated and unirradiated quantum dots. The Photoluminescence peak, intensity and lifetimes were found to vary with dose. At lower doses (up to 5kGy), they were found increasing and at higher doses (up to 20kGy) it decreased. The PL peak position also shifted toward low energy and broadened with increase of dose. Initial increase in PL intensity (upto 5kGy) is due to passivation of surface defects leading to high radiative recombination. At higher doses the damage of capping layer takes place leading to aggregation effects.

A Comparative Study Of Gamma, Electron Beam, And Synchrotron X-ray Irradiation Method For Synthesis Of Silver Nanoparticles In PVP 

Nilanjal Misra; Jayashree Biswal; V. P. Dhamgaye; G. S. Lodha; S. Sabharwal

Advanced Materials Letters, 2013, Volume 4, Issue 6, Pages 458-463
DOI: 10.5185/amlett.2012.ib.114

A one-pot synthesis method has been developed for preparation of silver nanoparticles in aqueous poly (vinyl pyrrolidone) (PVP) solution by synchrotron X-ray radiation. The hydrated electrons (eaq - ) and hydrogen atom radical (H·), products of radiolysis of water molecules by synchrotron X-rays brings about the reduction of the metal ions, resulting in homogeneous nucleation and nanoparticle formation. The nanoparticles were characterized by UV-visible spectroscopy and TEM analysis. A comparative study has been done to know the effectiveness of this synthesis method with that of gamma and EB- irradiation methods. In gamma radiation method the nanoparticle size obtained was ~8nm, whereas in synchrotron X-ray irradiation 10-15nm particles were obtained. Smaller size particles with narrow size distribution were obtained by g-radiolysis and EB-irradiation than those obtained by X-ray radiolysis. The effects of different experimental parameters, such as concentration of Ag + , PVP concentration on nanoparticle formation were studied.

Sensor Grade Nanostructured Thin Films Of Multicomponent Semiconducting Oxide Materials By Pulsed Laser Deposition

K. I. Gnanasekar; V. Jayaraman;T. Gnanasekaran; E. Prabhu

Advanced Materials Letters, 2013, Volume 4, Issue 6, Pages 464-475
DOI: 10.5185/amlett.2012.ib.115

High quality sensor grade nanostructured thin films of multicomponent semiconducting oxide sensors with superior sensitivity for monitoring trace levels of pollutant gases like NOx, NH3, H2 etc., in the ambient have been deposited by pulsed laser deposition technique. In-situ growth carried out at relatively lower temperatures yield granular films composed of nanocrystals of the desired crystallographic phase which otherwise would require high temperatures to stabilize. At some specific deposition conditions, growth of thin films containing uniform sized nano-grains with optimum inter-granular connectivity can be readily achieved. Here, we present the superior sensing properties of the sensor grade films of selected materials and bring out the unique characteristics of pulsed laser deposition technique for exploratory research in nano-structured thin films of materials not amenable to conventional synthetic routes. 

Microstructural Investigation Of Lipid Solubilized Microemulsions Using Laser Light Scattering

Suman Rana; Gunjan Verma;P. A. Hassan

Advanced Materials Letters, 2013, Volume 4, Issue 6, Pages 476-481
DOI: 10.5185/amlett.2012.ib.116

Solubilization of solid lipids in oil-in-water microemulsion is an important step in the preparation of lipid nanoparticles. Oil in water microemulsion has been prepared using Tween-80 (T-80) as a surfactant and isopropyl myristate (IPM) as an oil phase with a view to utilize them for the preparation of Solid Lipid Nanoparticles (SLN). The microstructure of the microemulsions were evaluated using laser light scattering studies. From light scattering studies, it was observed that the intensity of scattered light increases on increasing the concentration of IPM at a fixed concentration of T-80 (15%), reflecting an increase in the size of the micelles. Dynamic light scattering studies show that the hydrodynamic diameter of the micelles increases on increasing the concentration of IPM. Phospholipon® 90 G (lipid) solubilized microemulsions were prepared using 1:1 w/w mixture of lipid and IPM as the oil phase. DLS studies suggest that addition of lipid did not alter the size of microemulsion droplets significantly.

Synthesis, Characterization And Nonlinear Optical Properties Of Laser-induced Au Colloidal Nanoparticles

R. Kuladeep; L. Jyothi;D. Narayana Rao; K. Shadak Alee

Advanced Materials Letters, 2013, Volume 4, Issue 6, Pages 482-487
DOI: 10.5185/amlett.2012.ib.117

Gold (Au) colloidal nanoparticles (NPs) have been synthesized by direct irradiation of gold precursor (HAuCl4) solution in polyvinyl alcohol (PVA) matrix using nanosecond laser pulses at different irradiation fluencies and exposure times. Appearance of wine and dark wine colors indicated the formation of Au NPs. Transmission electron microscope (TEM) images exhibited spherical shaped particles and X-ray Diffraction (XRD) pattern confirms polycrystalline nature of Au NPs with cubic structure. Au NPs displayed negative nonlinearity and exhibited a shift from saturable absorption (SA) at lower intensities to reverse saturable absorption (RSA) accompanied by nonlinear scattering at higher excitation intensities in nanosecond regime at 532 nm. Two-photon absorption (TPA) is attributed to be responsible for the RSA behavior.

Nano Slit And Dot Array Pattern Of Au On SiO2 substrates Using Laser Beam Lithography

Pratap. K. Sahoo

Advanced Materials Letters, 2013, Volume 4, Issue 6, Pages 488-491
DOI: 10.5185/amlett.2012.ib.118

Highly monochromatic coherent light intensity of lasers provides the possibility of fabricating periodic nano-patterns which are needed in many applications. Here, we report 2D grating structure and periodic nano hole and dot arrays fabricated using two laser beam interference lithography. Using this method periodic grating as well as dot patterns have been fabricated with structure size of 50 -100 nm and pitch of 200-300 nm on SiO2 substrate. The nano-patterns are formed by inverting an array of photoresist posts by a lift-off process and subsequent reactive-ion etching using chromium as an etch mask. The depth of patterns can be tuned simple by laser dose to obtain high aspect ratio gratings. Transmission spectra measured in Au slits shows strong resonance features at 520 and 640 nm. Finite difference time domain simulations are used to estimate the near-field enhancement at the center of the slit pattern.

Self-assembled Microcones Generated On Solid Surface Through Pulsed Laser Irradiation

Sucharita Sinha; Anil K.Singh

Advanced Materials Letters, 2013, Volume 4, Issue 6, Pages 492-496
DOI: 10.5185/amlett.2012.ib.119

We present here our results on surface micro-structuring via nanosecond pulsed laser irradiation of Titanium and Stainless Steel cathode samples. Laser based surface micro-structuring leading to formation of self-assembled micro-tips can potentially enhance field emission efficiency of such surface treated cathodes. Microstructure of the laser treated surfaces has been observed under a Scanning Electron Microscope (SEM) and SEM images were further analyzed using software attached with Optical Microscope. To study the effect of laser fluence on developed surface microstructure, the target surface was irradiated in different regions with laser beams at varying laser fluence levels ranging from 2-10 J/cm 2 for a period of 1 to 15 minutes corresponding to 600 to 9000 laser pulses. Mean height of the generated micro-cones was observed to increase from 17 to 30µm on increasing number of irradiating laser pulses from 3000 to 9000 in case of Stainless Steel samples. In case of laser treated Titanium average periodicity of generated self-assembled micro-cones decreased from 10.8μm to 6.5μm when laser fluence was increased from 5 to 10J/cm 2 with a total of 600 laser pulses used for irradiating the sample.

Inhibition And Enhancement Of Spontaneous Emission Using Photonic Band Gap Structures 

Rajesh V. Nair; ;B N Jagatap; Anjani K. Tiwari; Sushil Mujumdar; and B N Jagatap

Advanced Materials Letters, 2013, Volume 4, Issue 6, Pages 497-501
DOI: 10.5185/amlett.2012.ib.120

We discuss experimental results demonstrating the inhibition and enhancement of spontaneous emission of dye molecules embedded in a nanophotonic structure. This is achieved in our all-solid self-assembled photonic crystals consisting of dye-doped polystyrene spheres. Our samples exhibit well-resolved photonic stop gap with high reflectivity and photonic strength. Laser induced emission experiments reveal an inhibition of ~ 70% of emission intensity in the photonic stop gap wavelength range. Also, we discuss the enhancement of spontaneous emission intensity near the blue side of the stop gap. Our results have implications in photonic devices, such as, low-threshold lasers and efficient lighting devices.

Surface-enhanced Raman Scattering (SERS) Spectroscopy For Trace Level Detection Of Chlorogenic Acid

Nandita Maiti; ;Tulsi Mukherjee; Sudhir Kapoor; and Tulsi Mukherjee

Advanced Materials Letters, 2013, Volume 4, Issue 6, Pages 502-506
DOI: 10.5185/amlett.2012.ib.121

Surface-enhanced Raman scattering (SERS) spectroscopy is one of the most sensitive tools for the detection of molecules adsorbed on nanometer-sized roughened metal surfaces. Additionally, SERS combines high sensitivity with the observation of vibrational spectra of the adsorbate, giving complete information on the molecular structure of the system under investigation. In this paper, good SERS substrates in the form of silver-coated films with an average size of ~16 nm particles were produced by reducing silver nitrate by neat formamide. SERS was then applied for the trace-level detection of chlorogenic acid (CGA) adsorbed over these silver-coated films. SERS spectra with good signal-to-noise (S/N) ratio, was achieved for the identification and characterization of CGA down to 10 -9 M concentration.