LSPR Peak Research Articles

High Performance Gold Dimeric Nanorods for Plasmonic Molecular Sensing

A metal dimeric nanostructure is an alternative design for a Localized Surface Plasmon Resonance sensor. At the dimer nanojunction, a high E-field enhancement (hot spot) is observed. In this work, nanostructure size parameters such as aspect ratio, junction, and length of gold dimeric nanorods (AuDNR) linked end-to-end by a thin dielectric junction were evaluated numerically, optimizing the sensing parameters of the plasmonic nanoplatform. The computational approach focused on the assessment of the LSPR extinction spectral peak shift to their local surrounding medium in order to estimate the behavior of sensing parameters such as the figure of merit (FoM), the bulk sensitivity ( η <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">B</sub> ) and the η <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">B</sub> × FoM. The nanostructure aspect ratio, junction, and rod length were evaluated, optimizing the plasmonic nanoplatforms sensing parameters. The optimized AuDNR achieved a high sensing performance with η <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">B</sub> = 544 nm/RIU and FoM = 12.4 RIU <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> . Moreover, the obtained η <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">B</sub> × FoM = 6745.6 nm/RIU <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> is the highest reported value in the literature. For molecular sensing, Campbell's model was explored to evaluate the wavelength shift as a result of molecular adsorption on the nanoparticle surface. We demonstrate that the dimeric nanostructure exhibit twice LSPR peak shift due to a thin molecular adsorption layer rather than a monomer of equivalent size. Our results show that optimized dimeric nanostructure is highly attractive for molecular identification, opening the possibility of establishing new nanoplatforms for medical diagnostic.

Synthesis of AgNWs Using High Molecular Weight PVP As a Capping Agent and Their Application in Conductive Thin Films

High molecular weight polyvinylpyrrolidone (PVP) and seeding conditions are considered to have important roles in the synthesis of AgNWs. In this work, we report a versatile synthesis of AgNWs in a salt-free environment and under Ar inert atmosphere using high molecular weight PVP and seeding step during the synthetic process. The high molecular weight PVP was found to efficiently promote the preparation of AgNWs via supporting the proper growth control of AgNWs on {111} facets and selective growth on {100} facets. The seeding step facilitates the formation of seeds such as multiple twinned nanoparticles (MTPs) and single crystal seeds, which promoted the feasible formation of AgNWs. The shape and size of the synthesized AgNWs were characterized by SEM and TEM. The crystalline nature of the synthesized AgNWs was characterized by HRTEM, SAED and XRD, and their LSPR peaks were confirmed by UV-Vis spectroscopy. The conductive properties of the synthesized AgNWs were determined by preparing their thin conductive film on a PET substrate. The prepared AgNWs thin films exhibited good sheet resistance.

A plasmonic biosensor array exploiting plasmon coupling between gold nanorods and spheres for domoic acid detection via two methods

An immunoassay was developed that utilized plasmonic coupling between immobilised gold nanorods and colloid gold nanospheres to detect the marine toxin domoic acid (DA). The aspect ratio of the nanorods was optimised and the effects of variation in acidity, silver to gold ratio, cetyltrimethylammonium bromide (CTAB) concentration and seed addition in the growth solution on the yield, size variance and LSPR peak position was investigated. Excellent nanorods (size variation < 15%; aspect ratio 3.5–5; yield 0.26–0.35 nM mL−1) were obtained for the LSPR range 785–867 nm using strong acidic conditions (12 µl HCl (37%)), silver to gold ratio of 1:5, 0.05–0.1 M CTAB and 20–30 µl seed addition to 10 mL of growth solution. One set of nanorods (54.9 X 15.7 nm; LSPR 785 nm) were immobilised onto a silica support and bio-functionalised with DA hapten. Colloid nanospheres (15 nm; LSPR 519 nm) were bio-functionalised with an anti-domoic-acid monoclonal antibody. The functionalised nanoparticles were used to detect DA by plasmon coupling by quantifying the average LSPR shift of individual plasmon couples with hyperspectral imaging or quantifying the pixels count caused by the particle aggregation visible under darkfield microscopy. The first method led to a LSPR blue-shift of ~55 nm caused by the immunoreaction. The second, simpler method, enabled very clear qualitative detection (p < 0.0005) of domoic acid when 10 µM domoic acid was added. Both methods show potential though the novelty and simplicity of the second platform allowing rapid (~30 min) detection with high-throughput possibilities using a simple set-up is of most interest.

LSPR biosensing for the early-stage prostate cancer detection using hydrogen bonds between PSA and antibody: Molecular dynamic and experimental study

Prostate specific antigen (PSA) as a prostate cancer marker has a significant role in screening the tumor in the initial stages. The LSPR is a versatile and robust technique among the PSA detection methods. In this study an ultra-sensitive label-free nanobiosensor was designed for determination of PSA at low concentration level in serum samples using antibody conjugated‑gold nanoparticle (GNP) and the high affinity binding mechanism of antibody/GNP probe with PSA protein was investigated by computational modeling. The first crystal structure of the complex between human PSA and monoclonal antibody (mAb) 8G8F5 were studied using molecular dynamics (MD) simulations. MD simulation also supports the formation of the antibody–PSA complex. The sensing principle is based on the LSPR peak shift produced by small changes in the refractive index of the dielectric medium around the probe upon binding to the antigen. The GNPs were synthesized by the citric acid reduction method and characterized by the UV–Vis spectrophotometry and dynamic light scattering. The 10 nm gold nanoparticles were covalently conjugated to the anti-PSA antibody and the affecting factors such as the concentration ratio of the antibody to Au NPs, pH and temperature were optimized. A detection limit of 0.2 ng mL−1, and calibration sensitivity of 43.75 nm/(ng mL−1) were obtained.

Enhanced RI Sensitivity and SERS Performances of Individual Au Nanobipyramid Dimers

Both the plasmon refractive index (RI) sensitivity and SERS performance of individual Au nanobipyramid (NBP) dimers are numerically investigated by finite element method (FEM). Each of the fractional shift of LSPR peak wavelength $$\lambda_{LSPR}$$ of Au NBP dimer’s longitudinal dipole mode and the corresponding RI sensitivity factor $$S$$ is unveiled to obey the universal “plasmon ruler” only for the scaled gap size being larger than 0.10, which is well elucidated in terms of the fractional shift of enhanced $$\left| E \right|_{\max }$$ around the gap region. The maximum $$S$$ and SERS enhancement factor G at gap distances 2 nm of Au NBP dimer are demonstrated to reach 618 nm RIU−1 and 4.5 × 1011, respectively, providing excellent plasmon RI sensitivity and SERS substrates. The enhanced S and G of Au NBP dimer than those of Au nanorod and nanoellipsoid counterparts under the same incident light and dimer geometry configurations are presented and discussed as well, respectively. The present work provides helpful clues for future designing Au dimer-based SERS substrates and LSPR RI sensors for chemical/biological sensing and detection.

Inter-band Transition in Citrate Capped Marks Dodecahedral Colloidal Gold Nanoparticles

Background: Optical properties of citrate capped dodecahedral gold nanoparticles have immense applications in a large variety of fields. The interband transition has a role in determining the optical behaviour of gold nanoparticles. Interband transition in citrate capped colloidal gold nanoparticles in the size range above ~5 nm has been left unattended for a long time. Objective: The present work is aimed at studying interband transition in citrate capped colloidal gold nanoparticles of size between ~5 nm and several tens of nanometres. Methods: Turkevich method and modified Brust method were used to prepare citrate capped colloidal gold nanoparticles. Transmission electron microscopy was used to determine their size and shape and their formation was explained with simulated figure obtained by Gnuplot programming. Interband transition was studied with the help of UV-Visible absorption spectroscopy. Results: Dodecahedral citrate capped colloidal gold nanoparticles of mean diameters 31.5 nm, 12.87 nm and 4.69 nm with LSPR peak positions at 528 nm, 524 nm and 509 nm were prepared. The interband peak of nanoparticles of all three sizes was found to be located at about 260 nm. Conclusion: Interband transition between Fermi level and 5d bands of the larger density of states in citrate capped dodecahedral colloidal gold nanoparticles of size above ~5nm leads to absorbance peak at ~260 nm, indicating a gap of ~4.77 eV between the Fermi level and closely spaced 5d bands. For smaller nanoparticles, absorption due to interband transition becomes more prominent relative to surface plasmon resonance absorption.

Magneto-plasmonic Co@M (M = Au/Ag/Au-Ag) core-shell nanoparticles for biological imaging and therapeutics

In this paper, the optical properties of magnetic-plasmonic core-shell nanoparticles are studied using the Mie theory and DDA method. DDA results are compared with Mie theory results for spherical core-shell NPs as it gives the exact solution. It is observed that the position of LSPR peak in core-shell nanostructures is tuned by changing the cores and shell thickness in the core-shell spherical nanostructures and aspect ratio as well as shell thickness in spheroidal core-shell nanostructures. In addition, the yolk-shell nanostructures exhibit enhancement of LSPR peaks, bandwidth, and their corresponding intensities, as compared to spherical core-shell nanostructures. The calculated absorption spectra at λmax are obtained in the wavelength range of 336-698 nm. This study opens up the new potential of appropriate core-shell nanostructures in bio-imaging, drug delivery, biomedicine, and therapeutic uses.

Plasmonic enhancement of betanin-lawsone co-sensitized solar cells via tailored bimodal size distribution of silver nanoparticles

Natural pigment-based photosensitizers are an attractive pathway for realizing low cost and environmentally friendly solar cells. Here, broadband light-harvesting is achieved using two natural pigments, betanin and lawsone, absorbing in the green and blue region of the solar spectrum respectively. The use of bimodal size distribution of AgNPs tailored for each of the pigments to further increase their efficiency is the key feature of this work. This study demonstrates a significant enhancement in current-density, voltage, and efficiency by 20.1%, 5.5%, and 28.6% respectively, in a betanin-lawsone co-sensitized solar cell, via plasmonic enhancement using silver nanoparticles (AgNPs). The optimum sizes of the nanoparticles have been calculated by studying their optical response and electric field profiles using Finite Difference Time Domain (FDTD) simulations, aimed at matching their resonant wavelengths with the absorption bands of the dyes. Simulations show that AgNPs of diameters 20 nm and 60 nm are optimum for enhanced absorption by lawsone and betanin respectively. The FDTD simulations of the plasmonic photoelectrodes demonstrated 30% and 15% enhancement in the power absorption by betanin and lawsone at the LSPR peaks of the 60 nm and 20 nm AgNPs respectively. An optimum overall concentration of 2% (v/v) and a ratio of 4:1 (20 nm:60 nm) of the bimodal distribution of the AgNPs, was determined for incorporation in the photoanodes. An average efficiency of 1.02 ± 0.006% was achieved by the betanin-lawsone co-sensitized solar cell with the bimodal distribution of AgNPs, compared to 0.793 ± 0.006% achieved by the non-plasmonic solar cell of otherwise identical configuration. Electrochemical impedance spectroscopy confirmed that the incorporation of the bimodal distribution of AgNPs in the solar cells also enabled enhanced electron lifetime and reduced recombination compared to the non-plasmonic counterpart, thereby improving the charge transfer. The plasmonic enhancement methodology presented here can be applied to further improve the efficiency of other natural dye-sensitized solar cells.

Plasmonic enhancement of light to improve the parameters of solar cells

Surface plasmon resonance (SPR) can be generated in metal nanostructures such as gold, silver, copper and aluminium, which are promising materials in the fields of optoelectronics and plasmonics. The SPR in periodic arrays has aroused great interest because of its uniform optical properties which can be applied in integrated optoelectronics device, including solar cells (SC). The optical spectra of structures with Ag nanoparticles on the surface of Si wafer were calculated. The simulation was carried out using finite-difference time-domain method (FDTD). The FDTD method is a powerful numerical algorithm for the direct solution of Maxwell's equations. As a source of radiation, a plane wave with a range of wavelengths 300–1240 nm is used. The enhancement of solar light absorption of structures with Ag nanoparticles has been demonstrated. The Localized Surface Plasmon Resonance peaks have been obtained in the wavelength range of 830–865 nm that is in good agreement with experimentally revealed one. It was shown that the period of Ag nanoparticles replacement significantly influences on the spectra and LSPR peak position. The measurement of current–voltage characteristics of solar cells with and without Ag nanoparticles demonstrated significant enhancement of short current density in case of AgNPs on SCs surface.

Al-Au Heterogeneous Dimer-trimer Nanostructure for SERS

Background: Tunability in resonance wavelength and the enhancement of the electromagnetic field intensities around the surface are two unique properties which make metal as a plasmonic material. A theoretical investigation on the LSPR and field enhancement for heterogeneous dimer–trimer metallic nanostructure by constituting Al and Au as two different plamsonic materials has been studied. Since electrons in Al exhibit free behavior for LSPR of Au, therefore, they influence the electric field magnitude generated by Au LSPR. Methods: The electromagnetic simulations reported in this paper were performed using the FDTD Solutions (version 7.5.1), a product of Lumerical Solutions Inc., Vancouver, Canada. We adopted a cubic Yee cell of 1 nm side and a time step Δt= 1.31•10-18 s, bounded by Courant condition. Results: The extinction spectrum shows LSPR peak over UV-visible region for isotropic nanostructure which shifts to NIR region for anisotropic shape nanostructure. The spherical shape hetero dimer nanostructure shows enhancement factor ~ 3.9 X 105 whereas it increases to ~ 6.2 X 106 for anisotropic shape at 610 nm. The field distribution corresponding to the trimer nanostructure reveals a large dipolar field distribution on each of the three nanoparticles, oscillating approximately in-phase. The spherical shape Al-Au-Al shows enhancement factor ~ 8.5 X 106 at 571 nm. The anisotropic shape increase the enhancement factor to ~ 2.4 X 107 at peak wavelength 700 nm i.e. tuning the plasmon wavelength towards NIR region. Conclusion: The tunability in plasmon wavelength and field enhancement factor has been evaluated for heterogeneous nanostructure over wider spectrum range i.e. DUV-Visible-NIR using Au-Al dimer and trimer nanostructure. The isotropic shape Au-Al hetero nanostructure shows larger enhancement in the UV-visible region, whereas the anisotropic shape nanostructure contributes towards the NIR region.

Controlling the oxidation state of molybdenum oxide nanoparticles prepared by ionic liquid/metal sputtering to enhance plasmon-induced charge separation.

Nanoparticles composed of molybdenum oxide, MoOx, were successfully prepared by room-temperature ionic liquid (RTIL)/metal sputtering followed by heat treatment. Hydroxyl groups in RTIL molecules retarded the coalescence between MoOx NPs during heat treatment at 473 K in air, while the oxidation state of Mo species in MoOx nanoparticles (NPs) could be modified by changing the heat treatment time. An LSPR peak was observed at 840 nm in the near-IR region for MoOx NPs of 55 nm or larger in size that were annealed in a hydroxyl-functionalized RTIL. Photoexcitation of the LSPR peak of MoOx NPs induced electron transfer from NPs to ITO electrodes.

Unraveling the role of cuprous oxide and boosting solar energy conversion via interface engineering in a Cu/TiO2 plasmonic photocatalyst

The presence of Cu2O covering in Cu/TiO2 composite can move LSPR peak out of inter-band transition range, create more interfaces, induce Fano resonance effect, facilitate hot electron injection, and may constitute a Z-Scheme of Cu2O/Cu/TiO2.

Dynamics of Binding of Lysozyme with Gold Nanoparticles: Corona Formation and its Correlation with a Naked-Eye-Based Colorimetric Approach

The interaction between colloidal gold nanoparticles (AuNPs) and lysozyme (Lyz) has been studied through spectroscopic and microscopic measurements, molecular docking simulation and colorimetric measurements to investigate corona formation and the mechanism, affinity, number of sites and stoichiometry of binding. Molecular docking simulation endorses that, at physiological pH, the interaction between basic NH2group of arginine and citrate ions is predominant than the interaction between citrate ions and the positive surface charge of the bare AuNPs that result in the desorption of citrate ions from Au surfaces and finally, electrostatic interaction between [Formula: see text] group of arginine and positive charge surface of AuNPs results in the adsorption of Lyz on Au surfaces. As observed from Benesi–Hildebrand and fluorescence analyses, the ground state complex formation between Lyz and AuNPs requires several minutes, which is approximately 11 min in the present work to attain stoichiometric ratio 1:1. CD spectra indicate insignificant or no conformational change in the secondary structure of Lyz in the presence of AuNPs. The time variation of LSPR peak position and peak height in the presence of Lyz have been studied extensively through spectroscopic and microscopic measurements. Detailed discussion on the probable time-specific roles of change in local dielectric constant, plasmon coupling and electrostatic interaction on these variations has been presented. Colorimetric change of the AuNPs-Lyz system with time has been analyzed by measuring the red, blue and green color fractions as well as its correlation with the process of corona formation and aggregation has been investigated to propose a novel naked eye colorimetric approach of studying these processes in AuNPs-Lyz system.

Localized surface plasmon resonance biosensing of tomato yellow leaf curl virus

Current techniques for plant virus detection, such as RT- PCR and ELISA, require multistep procedures and rely on sophisticated equipment. Due to the global spread of plant viruses, the development of simpler, faster and cheaper assay methods is inevitable. Gold nanoparticles (AuNPs) had raised much interest during recent years due to their novel optical properties or diagnostic purposes. The localized surface plasmon resonance (LSPR11LSPR: localized surface plasmon resonance.) of AuNPs had been used in the development of novel colorimetric nano-biosensing systems. The frequency and intensity of the LSPR peak generally depend on the shape, size and the surrounding medium of the AuNPs. In this study, unmodified AuNPs had been used to detect the unamplified Tomato yellow leaf curl virus (TYLCV) genome in infected plants. A specific DNA probe complementary to the coat protein region of virus genome was designed. The extracted total DNA of uninfected and infected plants was mixed with hybridization buffer and the designed probe. The mixture was denatured, annealed and then cooled to room temperature and was followed by AuNPs addition. The color changes in the samples indicating the presence of target virus infections were assessed visually after the addition of salt and confirmed by UV–Vis spectroscopy. The results showed that this strategy allowed for fast and sensitive detection of TYLCV genome and eliminated the need for PCR amplification and detection equipment.

Multifunctional nanotheranostic gold nanocages for photoacoustic imaging guided radio/photodynamic/photothermal synergistic therapy

In this work, we developed a novel multifunctional nanoplatform based on hyaluronic acid modified Au nanocages (AuNCs-HA). The rational design of AuNCs-HA renders the nanoplatform three functionalities: (1) AuNCs-HA with excellent LSPR peak in the NIR region act as contrast agent for enhanced photoacoustic (PA) imaging and photothermal therapy (PTT); (2) the nanoplatform with high-energy rays (X-ray) absorption and auger electrons generation acts as a radiosensitizer for radiotherapy; (3) good photocatalytic property and large surface area make AuNCs-HA a photosensitive agent for photodynamic therapy (PDT). In vivo results demonstrated that AuNCs-HA presented excellent PA imaging performance after intravenous injection, which provided contour, size, and location information of the tumor. Moreover, because AuNCs-HA could combine radiotherapy and phototherapy together, the tumors treated with AuNCs-HA showed complete growth inhibition, comparing to that with each therapy alone. Taken together, our present study demonstrates that AuNCs-HA is of great potential as a multifunctional nanoplatform for PA imaging-guided radio- and photo-therapy of tumor. Statement of SignificanceIn this study, a commendable theranostic nanoplatform based on hyaluronic acid modified AuNCs (AuNCs-HA) was developed. In our approach, the dilute solution of Gold(III) chloride is slowly dripped into Ag nanocubes solution, then the Au nanocages were obtained by redox reaction, and followed by HA modification. We explored them, simultaneously, as radiosensitizers for RT, photosensitizers for PDT, and therapeutic agents for PTT. Compared to that of each therapies alone, the combination of radio-therapy and photo-therapy results in a considerably improved tumor eliminating effect and efficiently inhibited tumor growth. In addition, AuNCs-HA exhibited remarkably strong PA signals for precise identification of the location, size, and boundary of the tumor, thereby facilitating imaging-guided therapy. In brief, our design of AuNCs-HA represents a general and versatile strategy for building up cancer-targeted nanotheranostics with desired synergistic imaging and therapy functionalities.

The Interaction of CdSe/ZnS Quantum Dot with Plasmonic Ag Nanoparticles Deposited on Amorphous Hydrogenated Carbon Thin Films

Local fields of metal nanoparticles can change quantum dots (QDs) absorption and luminescence. In this work, we have investigated the interaction of granulated Ag NPs films with CdSe/ZnS semiconductor QDs in hybrid structure with a-C:H thin films. We have studied hybrid structure with two a-C:H films on a quartz substrate having wider optical gap of 2.1 eV and narrow gap of 0.7 eV. The distribution of Ag NPs on the a-C:H was more ordered unlike a pure quartz surface. Homogeneous films of Ag NPs on a-C:H surface have narrower picks of LSPR in spectra. The intensity magnifying and the blue shift of the LSPR peak of Ag NPs on 31 nm in the spectra has been observed with an increase in the optical gap of a-C:H film. We have also compared how the properties of a-C:H films in hybrid structures with Ag NPs affect the absorption and luminescence of CdSe/ZnS quantum dots. The absorption maximum for the QDs on Ag NPs/a-C:H surface was higher than on Ag NPs on pure quartz. The red shift of the absorption peak was observed. We have observed photoluminescence quenching of the CdSe/ZnS QDs on the surfaces of the studied hybrid structures. The greatest quenching of QD luminescence was observed on quartz substrate. A less significant quenching of the CdSe/ZnS QDs luminescence was obtained in the sample with a-C:H film having a wider optical gap.

Gold core-satellite nanostructure linked by oligonucleotides for detection of glutathione with LSPR scattering spectrum

We demonstrated a sensitive method for detection of glutathione (GSH) based on LSPR scattering spectrum using gold core-satellite nanostructure linked by T-Hg2+-T base pair. The core-satellite assembly caused coupling between plasmonic nanoparticles, which inducing distinct change of LSPR peak wavelength. As the interaction between Hg2+ and GSH, the core-satellite nanostructure would be disassembled, which accompanied with spectral blue-shift of the scattering spectrum. By using this method, GSH could be quantitatively detected, and the detection limits can reach to 0.1 µM.

Single-Particle Study: Plasmon Damping of Gold Nanocubes with Vertices by Adsorbate Molecules

Figure S1. SEM image of AuNCs with an average diameter of 50 nm. Figure S2. A photograph to show experimental setup for single-particle DF microscopy and spectroscopy. Figure S3. More single-particle scattering spectra from AuNCs. A LSPR peak was observed at around 560 nm for AuNCs. Figure S4. Normalized scattering spectra of single AuNC in Figure 4(a) obtained at 3-min intervals. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

Cost-effective plasmonic device for label-free streptavidin detection

NLS was used to prepare holed plasmonic substrates with high sensitivity to streptavidin detection. SEM and AFM characterizations showed substrates with holes distribution of 240.1 ± 27.8 nm and periodicity of 420.2 ± 25.4 nm. These substrates showed a sensitivity of 382.40 ± 11.60 nm/RIU in solutions with different refractive indexes. The sensor has demonstrated high sensitivity in the biosensing of biotin-streptavidin. The immunoassay showed a 1.8 ± 0.3 nm LSPR peak redshift in the protein detection. This work forms a foundation towards the cost-effective plasmonic biosensors.

Spectroscopic ellipsometer study of laser ablation wavelength dependent growth kinetics of Ag nanoislands: An insight to potential plasmonic applications

Effect of inhomogeneous particle-size distribution on the effective LSPR peak position and broadening of the optical spectra of metal nanoislands thin films has been examined using Modified-Yamaguchi’s model (MYM). Effective dielectric constants (ɛ1, ɛ2) of the pulsed laser deposited metallic nanoislands thin films has been extracted using Spectroscopic Ellipsometer (SE) to provide an insight of laser ablation wavelength dependent growth kinetic of the films. Simultaneous fitting of polarized spectra along with psi and delta parameters strengthens the applicability of applied set of oscillators. Origin of negligible film roughness in ellipsometric results has been attributed to the plasmonic averaging of the spectra. Effective polarizability and the phase difference between transmitted and scattered wave have been calculated using ɛ1 and ɛ2. Present study shows the way of selecting laser ablation wavelength to deposit Ag nanoislands thin films as per the requirement of sensors and photovoltaic solar cells. A practical use of SE has been reported unlike previous studies which are limited to the measurement of dielectric constants only.