RESUMO
The trio elements found in Gunshot Residue (GSR) are considered the key elements that are characteristic of GSR. To date, most forensic laboratories have mainly concentrated on employing carbon stubs analyzed by Scanning Electron Microscopy (SEM) coupled with Energy Dispersive Spectroscopy (EDS) to find IGSR on the hands and clothing of a person. A little elevated from the normal practice, this work is focused on the evaluation of compositional and morphological variations of GSR collected from muzzle end, trajectory, and target obtained by firing the ammunition of choice (9×19 mm Indian ammunition). Even though there may be variations in IGSR compositions within various locations of a weapon, this hasn't been investigated or documented up to this point. To ascertain whether it is possible to identify any variation in GSR particles gathered from these three different locations, the objective of this study is to investigate the structural characteristics and elemental composition of GSR to identify the distinctive parameters that allow for comparison and to establish the composition of the primer. The study also focuses on assessing any possible surface modification that may occur to GSR upon striking the target and establishing a correlation between GSR particles and propellant powder. The collected GSR samples were analyzed using a digital microscope, SEM/EDS, and EDXRF. It was discovered that the primer type showed a strong correlation to the elemental composition and morphology of GSR. By analyzing the GSR particles collected from the various sites as mentioned above, it was possible to identify the primer mixture used in the ammunition and its diversity in elemental concentration. The obtained GSR samples were not spherical but showed an elongated structure and possessed a diameter ranging from 695.4 µm-1.640 mm, 536.2 µm-1.412 mm, and 775.8 µm-1.772 mm respectively. However, the morphology and the size distribution of the particles collected from all three different points showed slight deviation as moving from ME towards TG. The obtained results could identify the primer mixture and diversity in its elemental concentration. The morphology and size distribution of GSR collected from three different points showed deviations.
RESUMO
With thin film solar cell applications, chalcopyrite semiconductors present enormous potential for usage as an absorber layer. In today's electronics sector, wide band gap semiconductors have extreme demand for applications such as high-power, high-frequency, challenging devices that are resistant to high temperatures, optoelectronic devices, and short-wavelength light-emitting devices. The undoped and tin-doped CGS thin films are the subject of the current investigation. Pure and Tin (Sn) doped CGS thin films were produced on a glass substrate using a low-cost chemical spray pyrolysis technique in a nitrogen atmosphere. Spray pyrolysis is a flexible and efficient method for thin-film deposition. The process parameters, such as the nozzle distance, spray time, spray rate, and temperature, have a significant impact on the films' quality and characteristics. Fundamental characterization techniques, including XRD analysis, Micro Raman analysis, EDAX, UV-VIS-NIR spectroscopy, and Scanning Electron Microscopy (SEM), were used to examine the generated pristine and Sn-doped CGS thin films. The XRD patterns showed that the pristine and Sn-doped CGS thin films exhibit a tetragonal phase and there is a decrease in the crystallite size with increasing dopant concentration. SEM studies revealed that there is a change in the grain size and surface morphology of the film with increasing Sn doping concentration. The presence of copper (Cu), gallium (Ga), sulfur (S), and Sn was further confirmed by studying the EDAX spectrum. SEM results indicate that the surface morphology of the CGS films is modified by Sn doping. Further increasing the dopant percentage caused deformation and fragmentation of the sample. A comparison of the Raman spectra for pristine and Sn-doped CGS revealed that there is some substantial change in the layer composition after adding the dopant. Compared to the pristine CGS, the peak positions of CGS (1 wt %) and CGS (3 wt %) are not shifted but there is a significant change in the relative peak intensities and formation of an additional peak The Sn-doped CuGaS2 thin films had optical band gaps of 2.47 eV (0.0 wt% Sn-doped), 2.33 eV (1 wt% Sn-doped), and 2.58 eV (3 wt% Sn-doped). From this study, we can say that the 1 wt% Sn doped CGS sample is the best for solar cell application. The XRD results indicated that the Sn dopant addition in the CuGaS2 lattice site does not affect the symmetry of the material. Enhancement of absorption is done by the Sn dopant.
