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The fabrication and characterization of quantum dots-conjugated opal photonic crystals structure
Isnaeni,Cho, Yong-Hoon IOP Pub 2010 Nanotechnology Vol.21 No.22
<P>We have fabricated opal photonic crystal structure, which is assembled from quantum dots-conjugated polystyrene spheres. We found that the quantum dots (QD) emission from QD-conjugated photonic crystal (PC) structure experienced not only shifting to shorter wavelength, but also an asymmetrical broadening. This photonic crystal structure uses less quantum dots and may lead to great application such as single photon source and QD laser, since we may sharpen and broaden the QD emission by selecting the proper position of stop band. </P>
Development of a novel ozone gas sensor based on sol-gel fabricated photonic crystal
Rahmat, M.,Maulina, W.,Isnaeni,Miftah, D.Y.N.,Sukmawati, N.,Rustami, E.,Azis, M.,Seminar, K.B.,Yuwono, A.S.,Cho, Y.H.,Alatas, H. Elsevier Sequoia 2014 Sensors and actuators. A Physical Vol.220 No.-
We have developed a novel ozone gas sensor based on one dimensional photonic crystal with two defects. In this platform, the gas is dissolved in a specific neutral buffer kalium iodide reagent to include the Beer Lambert effect. The corresponding photonic crystal which was fabricated by using sol-gel method consists of a high refractive index layer of TiO<SUB>2</SUB> and a low refractive index layer of SiO<SUB>2</SUB>. Prior to the fabrication of corresponding photonic crystal, we grew the TiO<SUB>2</SUB> and SiO<SUB>2</SUB> single layer separately in order to ensure that the performance of each layer fulfilled the required characteristics provided by our simulation. After that, the fabrication processed was conducted layer-by-layer and inspected by spectrophotometer. The performance test of the fabricated photonic crystal, including its validation, accuracy and sensitivity, was then conducted through spectroscopic treatment and we used ozonizer as the gas source. Validation test was performed by comparing the results with measurement using NBKI method and showed a good agreement. It was found that the accuracy value is up to 98.75%. Based on a statistical approach, we found that the limit of detection is 1.067μg/m<SUP>3</SUP> ambient air.
S. Iwan,D. Dianisya,Riser Fahdiran,Isnaeni,Esmar Budi,Anggara Budi Susila,Erfan Handoko 한양대학교 세라믹연구소 2019 Journal of Ceramic Processing Research Vol.20 No.5
We have synthesized un-doped and Co-doped ZnO nanoparticles (NPs) by precipitation method at a temperature of 400 oC for 2 hours. According to the inorganic crystal structure database (ICSD) number #98-005-7478, the XRD pattern of ZnO NPs (average diameter of 99-144 nm) possess polycrystalline hexagonal wurtzite structure. The crystallite size of un-doped and 1.75 at.%, 3.79 at.%, 4.37 at.% Co-doped ZnO NPs are 20.81 nm, 19.84 nm, 43.85 nm, 37.95 nm, respectively. Meanwhile, the average micro-strain of the un-doped ZnO NPs and 1.75 at.%, 3.79 at.%, 4.37 at.% Co-doped ZnO NPs are 0.62%, 0.66%, 0.29%, 0.34%. These results confirm the crystallite size and micro-strain changing by Co incorporation. Further investigation, the Co incorporation into Zn site improve absorbance of ZnO NPs. Meanwhile, photoluminescence (PL) measurement shows that all ZnO NPs have one broad emission with centered peaks of 385 nm. It is indicating the substitution Zn2+ by Co2+ cause the distribution defect spread continuously in ZnO NPs structure
Iwan Sugihartono,Ridha Octa Alhuriyyah Azzahra,Nurfina Yudasari,Esmar Budi,Riser Fahdiran,Widyaningrum Indrasari,Tan Swee Tiam,Rahmat Setiawan Mohar,Isnaeni,Djoko Triyono,Fera Kurniadewi,Agus Setyo Bu 한양대학교 청정에너지연구소 2024 Journal of Ceramic Processing Research Vol.25 No.4
We have demonstrated green synthesis of ZnO nanoparticles using Moringa oleifera leaves (Mor-ZnO NPs) extractby co-precipitation method under 450oC for 2 hours with different pH-5, pH-7, and pH-8. The physical properties (i.e. structural, morphology, and absorbance) have been analyzed using X-ray diffraction (XRD) measurement, scanning electronmicroscopy (SEM), and ultraviolet-visible (UV-Vis) spectrophotometer. Furthermore, to investigate the functional group andantioxidant activity we performed Fourier transform infra-red (FTIR) analysis and 2,2-diphenyl-1-picrylhydrazyl (DPPH)assay. Structurally, all samples possess polycrystalline hexagonal wurtzite structure. Morphologically, the pH values affectthe morphology of Mor-ZnO NPs. Optically, the Mor-ZnO NPs with pH-8 have strong absorption in the range of shortultraviolet (200-280 nm). We predict that the basic pH value on green synthesize of Mor-ZnO NPs tune the near band edgeabsorption (NBA), which relates to the recombination of the free excitons. Whereas, based on the FTIR spectra analysis, theZn-O stretching can be identified at 442.67 cm-1, 458.67 cm-1, and 442.67 cm-1 for Mor-ZnO NPs with the pH-5, pH-7, andpH-8, respectively. According to DPPH assay, the Mor-ZnO NPs with pH-8 at 200 mg/ml has higher inhibition rate (67.7%). Hence, we believed that the Mor-ZnO NPs are potential antioxidants.