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Optical Properties of Toluene-soluble Carbon Dots Prepared from Laser-ablated Coconut Fiber Isnaeni, Isnaeni; Suliyanti, Maria Margaretha; Shiddiq, Muhandis; Sambudi, Nonny Soraya
Makara Journal of Science Vol. 23, No. 4
Publisher : UI Scholars Hub

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Abstract

In this study, we used laser ablation to fabricate toluene-soluble carbon nanoparticles from coconut fiber. In response to excitations at various wavelengths, the fabricated carbon nanoparticles exhibit three distinctive emission peaks at wavelengths of 300 nm, 440 nm, and 540 nm. These three emission peaks correspond to the  orbital state,  orbital state, and surface state, respectively. Photoluminescence excitation measurements indicate a high probability of energy transfer between the surface state and  orbital state, whereas the  orbital state is likely independent of the other states. The results of time-resolved photoluminescence measurements indicate that electrons are likely to remain longer in higher-energy states. Given that the carbon dots fabricated in this study were made from natural resources, these findings may find application in photonic devices that feature tunable emissions.
Determination of Band Gap Energy of ZnO/Au Nanoparticles Resulting in Laser Ablation in Liquid Julita, Mardiana; Shiddiq, Muhandis; Khair, Miftahul
Indonesian Journal of Chemical Research Vol 10 No 2 (2022): Edition for September 2022
Publisher : Jurusan Kimia, Fakultas Sains dan Teknologi, Universitas Pattimura

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.30598//ijcr.2022.10-mar

Abstract

The synthesis of ZnO and ZnO/Au nanoparticles using the laser ablation method in liquid has been successfully carried out. Characterizing the optical properties of ZnO and ZnO/Au using a UV-Vis Spectrophotometer (Ocean Optic MAYA Pro 2000) measured in the wavelength range of 275-875 nm. The characterization results obtained are absorbance and band gap values of ZnO and ZnO/Au nanoparticles. This study found the absorbance values of ZnO nanoparticles at wavelengths 330 and 335 nm. After obtaining the absorbance value, the band gap value was analyzed for ZnO and ZnO/Au nanoparticles, respectively, 3.23 eV and 3.17 eV. The decrease in the band gap value in ZnO is due to the presence of Au in ZnO nanoparticles which can replace one of the lattices in the ZnO crystal structure.
Surface Enhanced Raman Spectroscopy with La0.5Bi0.5FeO3-Based Substrates for Paraquat Pesticide Detection Tiawati, Nia; Triyono, Djoko; Shiddiq, Muhandis
Journal of Physics and Its Applications Vol 7, No 2 (2025): May 2025
Publisher : Diponegoro University Semarang Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.14710/jpa.v7i2.26211

Abstract

Paraquat is a highly toxic herbicide that poses serious environmental and health risks. Conventional detection methods are accurate but often complex and time-consuming. This study explores the use of La0.5Bi0.5FeO3 (LBFO) perovskite as a novel Surface-Enhanced Raman Spectroscopy (SERS) substrate. LBFO was synthesized via a sol-gel method and characterized using XRD, XRF, UV-Vis, and Raman spectroscopy. The LBFO-based substrate successfully enhanced the Raman signals of paraquat, enabling detection at concentrations as low as 6 ppm. These results suggest the feasibility of LBFO as an effective and low-cost SERS substrate for rapid paraquat detection.