The present work describes the formation of low-aspect-ratio Ag nanoparticles (NPs) arrays by sequential deposition of Ag from different growth directions on a nanoripple-patterned Si substrate, produced by low-energy ion beam irradiation. It is observed that the growth of Ag-NPs on ripple surfaces is direction-dependent due to the asymmetric ridge of the ripple pattern. This asymmetric ridge can be utilized to tune the shape of NP from elongated to spherical and in turn, assists in minimizing the LSPR anisotropy. The Finite-Difference-Time-Domain (FDTD) simulations demonstrate that the interparticle gap, major, and minor axis combinations of a NP are crucial in minimizing anisotropic near-field interaction. NPs grown perpendicular to the ripple from either direction lead to an elongated chain of nanoparticles; however, if a proper combination of sequential growth times is chosen then the aspect ratio of NPs can be tuned from elongation to spherical ones. Interestingly, a LSPR shift of 209 nm was observed when NPs are grown for 60 min on ripple patterns from one direction only. On the other hand, it reduces to 54 nm when NPs are sequentially grown for 30 min from each of directions, perpendicular to the ripples. SERS measurements also evidence a minimized anisotropic nature in sequentially grown NP arrays; hence, the growth direction as well as optimized growth times together can be used to control the LSPR anisotropy of NP arrays which can be used to fabricate such isotropic SERS substrates.

Ion beam sputtering (IBS) can induce nanoripple patterns in a short time on variety of materials for wide range of applications. In this work, we describe the nanoripple as well as terrace pattern formation by IBS on soda-lime glass surfaces and the mechanisms leading to such pattern formations. The role of ion energy, ion fluence, and ion incidence angle on the morphology of the structural features is systematically explored. For a range of ion beam parameter values with energy varying from 600 to 1500 eV and fluence in the range 9.7 × 1017 to 2.0 × 1019 ions/cm2 at fixed incidence angle of 45°, transition of ripples to terraces has been observed. The experimental results are explained on the basis of recently modified KS equation which clearly explains the simultaneous role of nonlinear cubic term in the terrace formation. It is also demonstrated how ion beam can be used to tailor the wettability of glass surface and makes it hydrophobic in nature. Due to pattern formation, anisotropic hydrophobicity is observed showing an increasing trend owing to the magnification of the amplitude of nanopatterns developed on the surface.

In this work, we report magnetic and optical anisotropies in tilted nickel (Ni) nanocolumns and their dependencies on the film growth conditions. The Ni nanocolumns were prepared using electron beam evaporation technique in conjunction with glancing angle deposition methodology. The film depositions were performed at various in-situ substrate temperatures viz. 30 °C, 150 °C, 250 °C and 300 °C. An increase in material density with in-situ substrate temperature due to the thermal diffusion mediated coalescence of neighbouring grains was observed. The results were further corroborated with the alterations in surface morphology of the films. The modification in tilt angle of the Ni nanocolumns was also observed with in-situ substrate heating due to the non-ballistic growth approach. The presence of uniaxial optical anisotropy was established in the films deposited at low substrate temperatures (< 250 °C) using generalized ellipsometry (GE). However, the uniaxial optical anisotropy was found to be negligible for the high temperature deposited films due to thermal diffusion effect. SQUID measurements were performed for quantification of magnetic anisotropy in the films. The estimated magnetic anisotropy energy confirmed low substrate temperature deposited films to be more anisotropic as compared to others. Magnetic coercivity of the films showed film porosity dependent changes in the field values. Overall, the present investigation demonstrates anisotropic behaviour of nanocolumnar nickel thin films for non-ballistic glancing angle deposition.

Saliva is a non-invasive sample for oral cancer detection due to the presence of cancer biomarkers. In this reported study, we investigated the potential use of SERS (Surface-Enhanced Raman Spectroscopy) for the non-invasive identification of oral cavity cancer by analysing the SERS spectra of saliva. We developed a SERS substrate by depositing Ag nanoparticles on glass ripples. SERS analysis was conducted on saliva samples collected from 10 oral cancer patients and 8 healthy volunteers having tobacco habits. The average spectra of cancer patient saliva and healthy volunteers' saliva show differences. Principal component analysis (PCA) and Linear discriminant analysis (LDA)-based multivariate statistical analysis were used for classifying the collected spectra. The PCA-LDA-based classification shows 70% sensitivity and 62.5% specificity. This study suggests that SERS analysis of saliva incorporated with PCA-LDA-based multivariate analysis is a potential tool for the non-invasive detection of cancer.

This study investigates the formation of facets on Si surface under Xe ion irradiation using an ion energy of 0.5 keV. By examining the effects of ion incidence angle (60 degrees -85 degrees), fluence (4.5 x 1018 to 1.35 x 1019 ions/cm2), and temperature (RT to 200 degrees C), we explore the evolution of facets. The surface roughness displays a distinct trend, reaching its peak when the ion incidence angle is 80 degrees, which indicates the formation of faceted structures due to a sudden change in roughness. Additionally, temperature studies highlight the important role of temperature in enhancing facet arrangement. To support experimental findings, numerical simulation using Anisotropic Kuramoto-Sivashinsky (AKS) equation is employed. These simulations provide valuable insights into the dynamics of facet evolution, allowing us to better understand how curvature-dependent sputtering yield, dispersion, and diffusion collectively influence the formation and morphology of facets on the Si surface under Xe ion irradiation.

A comparative wettability study was carried out on bulk polytetrafluoroethylene (PTFE) and physical vapor deposited PTFE-like thin films using low-energy Argon ion beam irradiation. Both bulk PTFE and PTFE-like thin film surfaces were irradiated with the beam energy of 300 and 800 eV for 5 min. The angle of incidence of the ion beam was varied from 0 degrees to 70 degrees with respect to the surface normal. Ion beam irradiation produced the tilted sharp-edged microstructures on PTFE sheets elongated in the direction of the beam. After irradiation with 800 eV at 20 degrees, the bulk PTFE sheet became superhydrophobic, the water contact angle increased from 105 degrees to 157 degrees, and again decreased to 132 degrees after irradiation at 70 degrees Whereas nanoripple-like patterns formed on PTFE-like thin films after ion beam irradiation. The maximum wavelength of such ripples was found to be 212 nm for an 800 eV irradiated surface at an angle of 50 degrees Beyond this angle, a clear transition from ripple to facet-like patterns was observed. The contact angles of the irradiated thin film were found to be varying from 105 degrees to 112 degrees up to 30 degrees irradiation and again decreased to 83 degrees after irradiation at 70 degrees PTFE thin film showed strong anisotropic wettability behavior with a variation of 12 degrees of contact angle values perpendicular to the ion beam direction, and water droplets did not roll off from the surface like in the case of bulk PTFE. X-ray photoelectron spectroscopy revealed that the bulk PTFE had C-C, and CF2 bonding on the surface, whereas PTFE thin films formed additional CF, CF-CFn, and CF3 bonding, which was not observed in the bulk PTFE. After irradiation, additional CFCFn and CF3 bonding in bulk PTFE were observed. However, in the case of thin films, ion irradiation causes severe chain scission, crosslinking, and defluorination of the surface.

Gap mode plasmonic coupling of noble metal nanoparticles with metal films makes them ideal candidates for manifold improvement in the surface-enhanced Raman scattering (SERS) efficacy via strong near-field enhancement in their gap realized by deposition of sandwiched dielectric spacer layers. This report presents an all-sputtering grown SERS substrate based on gap mode plasmonic coupling of Ag-NPs with Al films separated with thin dielectric overlayers of AlOx or polytetrafluoroethylene (PTFE). A remarkably high Analytical enhancement factor (as high as 3.7 x 109) with manifold SERS enhancement (as high as 26 times) is obtained with a limit of detection up to 10-13 M concentration of CV dye. Growth of thin dielectric over layer remains conformal on randomly orientated hillocks-like Al nanocrystallites (NCs) on Si substrates. Reflection studies show the broadband absorption of gap plasmon mode coupled Ag nanoparticles (NPs) and Al films. An optical model constructed using generalized oscillator model with the help of Lorentz and Tauc-Lorentz oscillators which reveals the localized surface plasmon resonance (LSPR) of Ag-NPs is strongly enhanced after gap mode plasmonic coupling (GMPC) in Ag-NPs and Al film based nanoparticles-on-mirror (NPoM) system. Finite difference time domain (FDTD) simulations validate the experimental findings that NPoM structure results in GMPC between AgNPs and underlying Al films. This study paves a way towards NPoM-based manifold enhancement in SERS-based detection efficacy of ultralow concentration of complex molecules.

Metanil yellow is a potential carcinogen that is commonly used as a food adulterant in turmeric powder. In this study, we detected Metanil Yellow from turmeric powder solution using a Surface Enhanced Raman Spectroscopy (SERS) substrate based on nano patterned soda-lime glass. Low amplitude ripples with an average wavelength around 65 nm was produced on commercially available soda-lime glass using low energy argon ion beam irradiation. Large area SERS templates were produced by growing self-organized ordered Ag nanoparticles on the rippled soda-lime glass. The optical analysis of the produced substrates shows the anisotropic plasmonic response and better Localized Surface Plasmon Resonance (LSPR) activity than Ag nanoparticles grown on rippled Si substrate. A biaxial layer consisting of Lorentz and Drude oscillators describes the real and imaginary parts of the dielectric function. The SERS analysis using Crystal Violet (CV) molecules demonstrates a five-fold improvement in the efficiency of silver grown on glass ripples than silver grown on Si ripples. We have tested the substrate for detecting Metanil yellow up to 10-6 M concentration in the water. Further, using the substrate, up to 10-4 M concentration of Metanil Yellow is detected from the turmeric solution.

Self-organized Ag nanoparticles arrays capped with Au layer are produced by depositing Ag nanoparticles on ion beam produced ripple patterned Si substrate followed by Au deposition. Au/Ag combination of nanoparticles shows intermediate plasmonic properties of Ag and Au nanoparticles by overcoming the associated drawbacks. Such combination redshifts the Localized Surface Plasmon Resonance (LSPR) compared to pure Ag and makes them suitable to excite the surface plasmon by both 532 nm and 785 nm laser for a wider range SERS application. The optimized Au deposition decreases the interparticle gap and elongates the nanoparticles along the ripple direction and makes a larger redshift in the LSPR. FDTD simulation also revealed that the electric field enhancement is higher along the ripple direction for both exciting lasers and shows that the LSPR of the com-bined Au/Ag system is shifted towards 785 nm. The limit of detection of Crystal Violet using the optimized Au/ Ag substrate is found to be 10-10 M for 532 nm laser and 10-8 M for 785 nm laser, respectively. The substrate shows good spatial uniformity with a relative standard deviation of less than 10% with SERS enhancement factors in the order of 104-105 for both lasers. These studies suggest that the as-prepared substrate is a promising candidate for detecting molecules sensitive to different wavelengths of laser excitation.

Low energy ion beam-induced nanoscale ripple patterns have attracted attention due to their use in various technological applications. Making defect free, highly regular, and low wavelength (similar to 30 nm) ripple patterns is still under investigation as ripple patterns form over triangular features (elevations and depressions) that curtail their use in an application. In this work using 300 eV Ar+ ion beam, the topographic evolution of such triangular features at elevated temperature up to 500 degrees C for ion fluences of 2 x 10(18) to 1 x 10(19) ions cm(-2) was examined. Triangular features remain intact well up to 200 degrees C with a marginal decrease in the base angle. Above 300 degrees C, triangular features start corrugating and, finally both triangular features and ripple vanished at 500 degrees C. The experimental findings were compared using modified anisotropic Kuramoto-Sivanshinsky (AKS) equation by Loew and Bradley (LB) incorporating simultaneously diffusion coefficient and third order dispersion term. Temperature-induced effects are adequately replicated; dispersion produces the triangular features and diffusion helps to grow it further. In experiment base angle and lateral length of the triangles decrease with increasing temperature, similar trend was observed in numerical simulations by varying the diffusion coefficient.

The nanoplasmonic behaviour of Ag decorated TiO2 film structure was spatially varied across the sample surface by utilizing the tailored optical response of the underlying dielectric TiO2 thin film prepared using a novel collimated glancing angle deposition technique (collimated-GLAD). A blue shift in maximum attenuation coefficient region and minimum film transmittance region of the Ag/collimated-GLAD TiO2 nanocomposite coating with increase in height from the evaporation source was detected. The presence of minimum transmittance region was found to have occurred due to localized surface plasmon resonance (LSPR) phenomenon with additional contribution from thin film interference. The measured transmittance spectra showed spatial selectivity in LSPR wavelength of similar to 22 nm with increase in height from the evaporation source. The variation of surrounding medium's (i.e. the TiO2 layer) refractive index (with height from the evaporation source) of the Ag nanostructures was the key factor responsible for the spatially varying nanoplasmonic response of Ag/collimated-GLAD TiO2 film across the sample surface. The Surface enhanced Raman scattering (SERS) characterization of the Ag/collimated-GLAD TiO2 film revealed photocatalysis driven dimerization conversion of p-aminothiophenol (p-ATP) molecules to p,p'-dimercaptoazobisbenzene (DMAB) due to the localized surface plasmons of the film structure along with the substantial enhancement in the Raman peak intensities compared to the blank substrate.

Ion beam sputtering, known as potential technique for producing nanoripple on various surfaces having wide range of applications. Along with nanoripple, triangular features are also superimposed, limiting their use for some potential applications. Here we are reporting evolution of triangular features on Ge (100) surfaces under low energy (300-1000 eV) Xe ion irradiation at room temperature for angles of incidence (61 degrees-80 degrees) and ion fluences of (5.34 x 10(17)-8.01 x 10(18) ions cm(-2)). Triangular features appear with the onset of ripple formation and disappear when the ripple periodicity is lost. These features formation depend not only on material but also depend on the ratio of the ion/target mass. In comparison with numerical simulations based on modified anisotropic Kuramoto-Sivanshinsky equation, we find good agreement for the evolution of base angle and lateral length for the triangular features with ion incidence angle. The dynamics of triangular feature with ion incidence angle and ion fluence have been reported. Ion-incidence angle dependency is adequately replicated in numerical simulations. Experimentally the base angle and lateral length increases with increase in ion incidence angle, similar trend is observed in numerical simulation.

Lower sputtering yield of the discharge wall material is a crucial parameter for the performance of Hall Effect Thruster (HET). In this article, we report the sputtering yield of HET wall material BNSiO2 (borosil) at elevated temperature similar to 600 degrees C using quartz crystal microbalance (QCM). We observe a linear increase in the sputtering yield with temperature and it remains stable during long duration experiments using Xe ions. Two different crystallographic orientations of borosil give a slight variation in the yield. The higher yields for higher operating temperatures is proposed to be due to the thermal spike nature. Microscopic surface morphology shows only different grains of BNSiO2, however high resolution nanoscopic view reveals the formation of nanoripple like structures over different grains. The periodicity of such features increases with ion dose (sputtering time) and temperature in the range of 70-190 nm. Local curvature dependent erosion plays crucial role in such pattern formation.

Extraordinary performance of nonvolatile memories based on resistive switching is expected to fulfill the re-quirements of next-generation data-intensive technologies. However, due to the separate growth of functional layer and electrodes in the device, resistive random access memories still suffer from their implementation at a commercial scale. Herein, depending upon the polarity, a single device is used to grow Ti thin film followed by plasma fireball-mediated oxygen ion implantation to transform the top surface of Ti film into a functional TiOx layer to fabricate the device. The formation of TiOx layer at the near-surface region and oxygen-concentration gradient with depth in the implanted film is demonstrated. The current-voltage characteristics of the device analyzed at the nanoscale show forming-free bipolar resistive switching, which is further confirmed by the twofold erase-write process. At 5 x 1016 ions cm-2 fluence, resistive switching occurs at higher voltages, while at 5 x 1017 ions cm-2 fluence, it occurs at lower voltages. As an application, the rapid fabrication of periodic arrays of squared memory cells of different sizes is demonstrated. We propose a simple and cost-effective one-step technique to fabricate resistive switching-based nanoscale nonvolatile memory devices, which can be utilized for the production of high-density commercial devices at a large scale.

The bouncing dynamics of impacting water droplet on low energy ion beam produced superhydrophobic PTFE surfaces was investigated for the self-cleaning application. Ion beam with 300 eV and 800 eV energies was used to produce nanostructures on PTFE surfaces having the bouncing behaviour. The bouncing dynamics of water droplet was studied using dynamics parameters like spreading factor (beta), contact time (t(c)), time of flight (t(a)) and number of bounces. The maximum spreading factor for the impact velocity of 0.5 m s(-1) and 1.0 m s(-1) was found to be 1.4 and 2.0, respectively for both 300 eV and 800 eV irradiated surfaces. The contact time of impacted droplet on 800 eV irradiated surface with 0.5 m s(-1) velocity was found to be much lower (t(c) = 13.00 ms) than 300 eV ion irradiated surface (t(c) = 19.67 ms). Post impact bouncing number as high as 14 was found for 800 eV irradiated surface. Depending on ion energy and irradiation time the surface was converted from complete wetting to complete bouncing at low impact velocity of 0.5 m s(-1) and from complete bouncing to partial bouncing at 1.0 m s(-1). The self-cleaning property on 800 eV irradiated surface was successfully demonstrated using carbon powder.

Ellipsometry is a versatile optical measurement technique which uses polarized light as a probe to characterize various properties of materials viz. film thickness, dielectric functions, uniformity, etc. by detecting the change in the polarization state. In spite of the basic applications, ellipsometry technique is highly used in advanced plasmonic applications like characterization of plasmonic -waveguides, -switches, -tweezers, -circuits, metamaterials, etc. In this chapter, we present the sub-wavelength plasmonic response of Ag and Au nanoparticle-nanowire arrays and nanodot patterns which can be characterized using spectroscopic, generalized, and Mueller matrix ellipsometry modes. In particular, probing local surface plasmon resonance (LSPR), tuning LSPR by varying size, shape, particle number density, or interparticle-gap along or across the nanoparticle arrays, probing ordering of metal nanoparticles along the arrays, detecting in-plane or out-of-plane optical anisotropies, optical modelling of anisotropic systems, directional dielectric functions of anisotropic arrangement of metal nanoparticles, annealing-dependent lost-of-anisotropy are of prime interest.

Ion beam irradiation produced ripple nanopatterns on Si surface was used to produce a highly dense and sensitive SERS substrate for detecting Dichlorvos pesticide below the permissible limit. The wavelength of the ripple varied from 22 nm to 35 nm by changing ion beam energy from 200 eV to 500 eV. Highly regular nanoparticles arrays were produced down to 22 nm wavelength choosing the proper ion beam parameter and ripple orientation during deposition. The shape of deposited nanoparticles on ripple nanostructures changed from elongated to spherical upon increasing wavelength and amplitude of ripples at different ion energies. The optimization of SERS intensity was carried out using crystal violet dye which revealed that the maximum enhancement (enhancement factor similar to 10(7)) occurred for the 300 eV irradiated substrate. The optimized substrate was used for detecting Dichlorvos up to 1 ppm level without using any binder molecule.

Over the last decade, research has intensified worldwide on the use of low-temperature plasmas in medicine and healthcare. Researchers have discovered many methods of applying plasmas to living tissues to deactivate pathogens; to end the flow of blood without damaging healthy tissue; to sanitize wounds and accelerate its healing; and to selectively kill malignant cancer cells. This review paper presents the latest development of advanced and plasma-based technologies used for applications in neurology in particular. Institute for Plasma Research (IPR), an aided institute of the Department of Atomic Energy (DAE), has also developed various technologies in some of these areas. One of these is an Atmospheric Pressure Plasma Jet (APPJ). This device is being studied to treat skin diseases, for coagulation of blood at faster rates and its interaction with oral, lung, and brain cancer cells. In certain cases, in-vitro studies have yielded encouraging results and limited in-vivo studies have been initiated. Plasma activated water has been produced in the laboratory for microbial disinfection, with potential applications in the health sector. Recently, plasmonic nanoparticle arrays which allow detection of very low concentrations of chemicals is studied in detail to allow early-stage detection of diseases. IPR has also been developing AI-based software called DeepCXR and AIBacilli for automated, high-speed screening and detection of footprints of tuberculosis (TB) in Chest X-ray images and for recognizing single/multiple TB bacilli in sputum smear test images, respectively. Deep Learning systems are increasingly being used around the world for analyzing electroencephalogram (EEG) signals for emotion recognition, mental workload, and seizure detection.