Search for: All records

This study investigates the optical properties of ion-bombarded Au-SiO2 nanocomposites, focusing on the enhanced Fano resonance observed in these samples. The formation of nanocrystals and nanocavities due to ion bombardment leads to significant interactions between plasmonic and vibrational modes, resulting in pronounced Fano resonance in the strong coupling regime. The study aims to explain the closer spacing of modes, the elevated baseline absorbance, and the asymmetric lineshape observed in the ion-bombarded samples. A detailed analysis is provided, comparing these findings with other sample preparations, such as Au-coated SiO2 and 20 nm Au colloidal on SiO2. The implications of these results for understanding plasmonic behavior and their potential applications in nanophotonics are discussed. 

Nowadays there is a great demand for LED bulbs which are replacing incandescent light bulbs. LED bulbs are compact, rugged, and free from pollution. Diodes emit a single wavelength. However, phosphor coated diodes generate white light on exposure to blue or violet light. Global research is ongoing to design phosphor coatings which emit high intensity in a broad spectral wavelength region. We are also investigating different phosphor materials to address this issue. We are investigating the suitability of europium doped crystals and glasses for this purpose. Crystals used for this study were procured from commercial sources and the glasses were made in our laboratory by the melt quenching technique. The glass samples were then polished with sandpapers of different grades. Detailed spectroscopy measurements were performed to characterize the materials. Absorption spectral measurements of the materials were performed using a Cary 3E spectrophotometer. Emission was stimulated from the samples by exposing them to blue or violet diode lasers. A compact spectrometer was used for fluorescence spectral measurements. Emission spectral data and lifetime measurements were used for unambiguous spectroscopic assignments. From the emission spectral measurements, color coordinates and color temperature were derived. 

Tellurium oxide-based glasses were made by the melt quenching technique. Appropriate quantities of the chemicals were weighed, mixed/ ground, and then melted above the melting point for an hour. Samarium and Silver compound were added to the starting chemicals. The melt was poured into an aluminum mold to get different shapes and sizes. The spectroscopic characterization of the samples was done by using different laser excitation sources. Silver metallic particles were induced by heat treating the glass above its glass transition temperature. Absorption and emission measurements revealed enhanced characteristics. 

This research explores Microwave Plasma Chemical Vapor Deposition (MPCVD) for depositing diamond films on steel alloys (316L, 4140, and 1018) with a vanadium carbide interlayer to enhance adhesion and compatibility. The study reveals that a soft vanadium carbide interlayer and the FCC lattice match lead to a Ta-C film. The results of the graphite inhibition and diamond deposition varied with the steel alloy underlayer composition. In the 316L steel alloy, we successfully formed a thick, compressive strain-induced, sp3-bonded tetrahedral amorphous carbon layer without graphite. The findings have wide-ranging applications in environments demanding high durability and thermal conductivity. 

This study explores the impact of CaTiO3 and LiNbO3 crystals on the optical and dielectric properties of polyvinylidene fluoride (PVDF) films. Our investigation employs UV–Visible Spectroscopy to characterize the n-π* CF related electronic transition within the PVDF matrix. We find that CaTiO3 crystals significantly decrease the composite’s band gap and dielectric properties, enhancing its electronic and optical attributes. Conversely, LiNbO3 crystals increase the band gap energy. These variations align with observed DC conductivity changes, suggesting novel functionalities for optoelectronic, sensing, and energy storage applications. 

Barium borate glasses embedded with Sm³⁺and/or Silver oxide were made by the melt quenching technique. Silver particles were induced by heat treatment. Imaging and spectroscopy measurements were performed to characterize the samples.