Departments of Physics

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    UV-VISIBLE SPECTROSCOPIC QUANTIFICATION OF SUN SCREENING EFFICIENCY OF SOME HERBAL EXTRACTS AND COMMERCIALLY AVAILABLE BODY CREAMS AND SUNSCREENS IN ETHIOPIA
    (HAWASSA UNIVERSITY, 2024-06) KENEAN DAGNE RORISA
    In this study, the sun protection factor (SPF) of different plant extracts, as well as commercial sunscreens and body cream, was evaluated using the UV-Visible spectroscopic approach, which is quick, simple, and inexpensive. The in vitro SPF value is estimated using the spectrophotometric method proposed by Mansur et al. After dilution with ethanol solutions, five herbal extracts, Ocimum lamifolium hochst (Damakese), Rhamnus prinoides (Gesho), Vernonia amygdalina (Grawa), Thymus schimperi (Tosign), and Trigonella foenum-graecum (Abish), were prepared, and the absorbance was measured between 290 nm and 320 nm. All of the examined herbal extracts were found to have some level of UV protection; the highest SPF value was 5.86 for Rhamnus prinoides (Gesho) extract, while the lowest was 0.93 for Ocimum lamifolium hochst (Demakese) extract. The same technique was applied to determine the SPF values of commercial body cream and sunscreens. The examined samples, Lady Diana, Valera, Dr. Rachel, and Super White's - labeled SPF values were in the range of 30 and 60. After evaluation, the results of the analysis showed that all of the selected samples had SPF values lower than what was written on the label. This discrepancy raises questions about the product's effectiveness and reliability. Commercial products shield the skin from UV rays; however, prolonged exposure may result in negative effects on the skin. The impact of chemical sunscreens must be countered by an alternative. This study examined the possible photo-protective qualities of natural substitutes, especially herbal extracts, in response to these concerns.
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    INVESTIGATION OF STRUCTURAL AND OPTICAL PROPERTIES OF MANGANESE DOPED COPPER OXIDE THIN FILM SYNTHESIZED BY CHEMICAL BATH DEPOSITION METHOD
    (HAWASSA UNIVERSITY, 2024-11) DESALEGN FENTAHUN TADEGE
    This study investigates the synthesis and characterization of manganese-doped copper oxide (CuMnO) thin films deposited onto glass substrates using the chemical bath deposition (CBD) method. The objective were to understand how varying manganese concentrations affect the structural and optical properties of the films. The process involved preparing solutions with varying manganese sulfate concentrations (1.5 ml, 3 ml, 4.5 ml, and 6 ml) and maintaining constant conditions for copper acetate, ammonia and hydrazine. The films were deposited at 50°C for 30 minutes, followed by annealing at a temperature of 300°C for 1 hours and 30 minutes. Structural analysis using X-ray diffraction (XRD) revealed that the films possessed a monoclinic copper manganese oxide and cubic Cu2O structure .The crystallite size initially increased with manganese concentration, reaching a maximum at 4.5 ml, before slightly decreasing. The dislocation density and strain showed corresponding trends, indicating improved crystal quality up to a certain concentration. Optical properties were assessed using UV-Vis spectroscopy. The band gap of the films increased from 1.7 eV to 1.9 eV as the manganese concentration rose from 1.5 ml to 6 ml. This shift in the band gap reflects the impact of manganese doping on the electronic structure of the films, potentially enhancing their suitability for optoelectronic applications. Overall, the results demonstrate that manganese doping effectively tunes the structural and optical characteristics of CuMnO thin films, offering insights into their potential use in various technological applications, including sensors and photovoltaic devices