Browsing by Author "Dr. M Junaid Amjad"

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A comprehensive study of Plasmon Emission in Lanthanide Doped Bio-glasses
(Library Information Services, COMSATS University Islamabad, Lahore Campus, 2022) Saba Younas Rana; CIIT/SP21-RPH-006/LHR; Dr. M Junaid Amjad; LHR TP 8153
In this work, sol–gel-based erbium Er3+ doped with or without silver bioactive glass powders were prepared. Rare earth (RE) elements exhibit similar nature and have free electrons, this property enable them to react with almost every element that is why they are used in modern technologies. RE ions have excellent spectral and chemical properties. Rare earth silicate based glass materials show promise for optical, photonic, and biomedical uses. Plasmonic nano silver impact photoluminescence spectroscopy of silicate based glass co-doped with Er3+ ions. Some rare earth ions convert the wavelength of incident light into shorter wavelength. This is an anti-stoke process and known as up-conversion. In recent era, up-conversion (UC) process have been discussed due to their applications in many fields, such as bio-imaging, solar cells etc. Although UC is very important but unfortunately it is not an efficient phenomenon which means if many lower energy photons get absorbed in material, only one higher energy photon get emitted. To enhance the UC process, plasmonic nanostructures have been used which may increase the efficiency of up-converting materials. It is investigated that rare earth Silver NPs co-doped in glass material has luminescence effect due to surface Plasmon resonance (SPR). Surface Plasmon resonance (SPR) is collective oscillation of electrons in metal surface due to these oscillations, electric field produced around (NPs). Plasmonic NPs with RE ions, enhance the spectral properties and increase optical transition by intensive electric field. The main purpose of silicate based glass co doped with RE and Ag NPs is to investigate the SERS effects and obtain stable glass substrate. Enhanced Photoluminescence of RE ions in glass containing silver species occurred due to the surface plasmon resonance (SPR) and it can enhance many optical phenomena. It is also described that silver acts as a sensitizer for RE ions in glass. The higher visible emission spectra under excitation of 488 nm was observed. Increased heat treatment can increase the concentration of NPs and it can cause quenching effect in intensity of Dy3+ ion. Advanced techniques, such as Raman, PL (photoluminescence), and FTIR, are used to study the optical, structural and morphological characteristics of these glasses. The results demonstrate absorption and luminescence spectroscopy, as well as the excited state lifetime, which influences the optical characteristics of the glass. Photoluminescence characteristics were investigated in detail. The steady state photoluminescence and decay kinetics of the samples were investigated under excitation (488 nm) where only Er3+ close to Si nano clusters can be excited. All the samples prepared in the study exhibited bright green emission upon excitation at 488 nm. Results showed that the dopant concentration and the sample morphology have significant influence on the photoluminescence and decay properties of the glasses. Sol–gel-derived bioactive glass particles exhibited stronger emission intensity.
Effect of Silver on Luminescence of Dy3+ doped Sodium-Borophosphate Glass
(Library Information Services, COMSATS University Islamabad, Lahore Campus, 2020) Sara Abid; CIIT/FA18-RPH-010/LHR; Dr. M Junaid Amjad; LHR TP 6080
free electrons, this property enable them to react with almost every element, that is why they used in modern technologies. RE ions have excellent spectral and chemical properties. Some rare earth ions convert the wavelength of incident light into shorter wavelength. This is an antistoke process and known as upconversion. In recent era, upconversion (UC) process have been discussed due to their applications in many fields, such as bioimaging, solar cells etc. Although UC is very important but unfortunately it is not an efficient phenomenon which means if many lower energy photons get absorbed in material, only one higher energy photon get emitted. To enhance the UC process, plasmonic nanostructures have been used which may increase the efficiency of upconverting materials. It is investigated that rare earth Silver NPs co-doped in glass material has luminescence effect due to surface Plasmon resonance (SPR). Surface Plasmon resonance (SPR) is collective oscillation of electrons in metal surface due to these oscillations, electric field produced around (NPs). Plasmonic NPs with RE ions, enhance the spectral properties and increase optical transition by intensive electric field. NPs with RE ions has been observed in solution, polymers and glass but glass has been preferred because of easy fabrication, versatility in shapes, transparency and other spectral properties. These desirable characteristics of glass made them applicable in many fields but still upconversion enhancement is big challenge which is being discussed for practical applications. Choosing glass host material is also been discussed, usually Silica based glass materials can be obtained at very high temperature as compared to phosphate and phosphate-based glasses, so it is preferred over Silica glass. Borophosphate glass also nominated as an active host for metal NPs growth and to enhance the electromagnetic field for SERS applications, an active glass is required. The main purpose of making borophosphate glass co doped with RE and Ag NPs is to investigate the SERS effects and obtain stable glass substrate. Glass substrate prepared by melt quenching using raw powder compacted into crucible and heated in electric furnace. Then glass material poured into stainless steel plate at cooled down at room temperature. It has been investigated that glass matrix containing Dy3+ aimed to study the sensitizing effect of metal species to enhance the Luminescence of Dy3+ ion.