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Spektra: Jurnal Fisika dan Aplikasinya

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Published by Universitas Negeri Jakarta

ISSN : 25413384 EISSN : 25413392 DOI : -

Core Subject : Science, Engineering,

Aerospace Engineering Electrical & Electronics Engineering Energy Materials Science & Nanotechnology Physics

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Articles 260 Documents

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Back Matter SPEKTRA Volume 9 Issue 3, December 2024 Spektra, Editor
Spektra: Jurnal Fisika dan Aplikasinya Vol. 9 No. 3 (2024): SPEKTRA: Jurnal Fisika dan Aplikasinya, Volume 9 Issue 3, December 2024
Publisher : Program Studi Fisika Universitas Negeri Jakarta

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.21009/SPEKTRA.093111

Influence of Polymer Matrix on The Morphology and Crystallization Behavior of Electrospun Zinc Oxide Fibers Aprilia, Annisa; Permana, Diki; Safriani, Lusi; Fitrilawati, Fitrilawati
Spektra: Jurnal Fisika dan Aplikasinya Vol. 10 No. 1 (2025): SPEKTRA: Jurnal Fisika dan Aplikasinya, Volume 10 Issue 1, April 2025
Publisher : Program Studi Fisika Universitas Negeri Jakarta

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.21009/SPEKTRA.101.01

ZnO finds widespread applications such as in photocatalysis, sensors, medicine, and other optoelectronic devices. The characteristics of ZnO can be influenced by several parameters, one of which is morphology. Fiber structures are attractive for research among various shapes and sizes due to their large effective surface area. ZnO fibers can be produced using electrospinning. However, the fiber morphology strongly depends on several important parameters, one of them is the characteristics of the polymer as a matrix. The molecular weight and concentration of the polymer and precursor material influence the solution viscosity, which is one of the crucial parameters in the electrospinning method. In this study, ZnO fibers were fabricated using three different polymers as matrices: PVP (polyvinyl pyrrolidone), PVAc (polyvinyl acetate), and PVA (polyvinyl alcohol). This research investigates the influence of polymer type on the morphology of ZnO fibers and crystallization behavior based on thermal characteristics. Based on SEM results, ZnO fibers were successfully fabricated with diameters ranging from 20–90 nm. The different characteristics are related to the type of polymer matrices and heating treatment. Only the PVA polymer could produce fibers before and after calcination, whereas the PVAc polymer-based fiber vanished after calcination. The disappearance of the fiber morphology is probably caused by the relatively high precursor (ZnAc) concentration, which leads to damage to the fibers formed during the calcination process. PVP failed to produce fibers, possibly due to its low polymer molecular weight, necessitating adjustment of other parameters. The removal of organic compounds through calcination continued until a temperature of 450ºC was reached. However, organic compounds were still identified in the samples based on FTIR characteristics. The ZnO/PVA fibers have hydrophobic surfaces, with the contact angle of water droplets being 117.75º. This characteristic is ideal for several applications such as antibacterial compounds or self-cleaning materials. Considering the inherent properties of ZnO, it can function as both an antibacterial and a photocatalytic agents simultaneously.

Stem-base Rot Disease Detection in Oil Palm using RGB (Red, Green, Blue) and OCN (Orange, Cyan, NIR) Image Fusion Method Based on ResNet50 Panggabean, Prima Ria Rumata; Rista, Rista; Saputro, Adhi Harmoko; Handayani, Windri
Spektra: Jurnal Fisika dan Aplikasinya Vol. 10 No. 1 (2025): SPEKTRA: Jurnal Fisika dan Aplikasinya, Volume 10 Issue 1, April 2025
Publisher : Program Studi Fisika Universitas Negeri Jakarta

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.21009/SPEKTRA.101.02

Current image acquisition and processing methods still need to be improved to effectively detect oil palm diseases. A precise and fast method to detect stem base rot disease in oil palm trees can be developed using drone technology and image processing approaches. An OCN (Orange, Cyan, NIR) camera is added to a standard drone and equipped with an RGB (Red, Green, Blue) camera. Combining the two cameras is proposed to generate multispectral imagery using an image fusion method called early fusion. A Multispectral Convolution Neural Network (MCNN) is also introduced to detect stem base rot disease by analysing the leaf patterns of oil palms. Healthy and unhealthy leaf samples were collected from oil palm plantations in Bogor. The images that have passed the image processing stage with the fusion method become inputs for modelling to identify stem base rot disease in oil palm. The results of the research using the multispectral image fusion method (RGB and OCN) based on the ResNet50 architecture can be used to identify stem base rot disease in oil palm effectively, as evidenced by the training and validation accuracy of 97.75% and 96.48%.

Enhanced Optical Properties of Ce-Doped ZnO Nanoparticles via A Green Plant-Based Synthesis Approach Simatupang, Mediniah Putri; Ari Sulistyo Rini; Erwin
Spektra: Jurnal Fisika dan Aplikasinya Vol. 10 No. 1 (2025): SPEKTRA: Jurnal Fisika dan Aplikasinya, Volume 10 Issue 1, April 2025
Publisher : Program Studi Fisika Universitas Negeri Jakarta

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.21009/SPEKTRA.101.03

This study investigated the optical properties of Ce-doped ZnO nanoparticles (Ce/ZnO), synthesized using Pandanus ammaryllifolius leaf extract via a green biosynthesis method. Ce doping concentrations of 1%, 2%, and 3% were applied, and the nanoparticles were annealed at 400 °C for two hours. UV-Vis analysis showed a redshift in the annealed samples, with the wavelength increasing from 368 nm to 370 nm, likely due to particle growth after thermal treatment. In contrast, the unannealed samples exhibited a blueshift, with the maximum absorbance wavelength decreasing from 361 nm to 356 nm. The absorbance values were higher in the annealed samples than in the unannealed ones. The band gap energy of doped ZnO samples decreased slightly after annealing, from 3.20–3.22 eV to 3.15–3.19 eV, indicating improved optical properties. FTIR analysis revealed the presence of Ce–O bonds and functional groups, such as O–H and C–H, with sharper peaks in the annealed samples. The novelty of this study lies in utilizing Pandanus ammaryllifolius leaf extract as a natural reducing and stabilizing agent, providing a sustainable and eco-friendly alternative to conventional chemical synthesis methods. The findings suggest that Ce doping enhances the optical properties of ZnO nanoparticles, making them suitable for specific applications in environmental remediation, such as the degradation of organic pollutants, and in technological fields like photocatalytic devices and UV-absorbing materials.

Technical and Environmental Performance Evaluation of Fuel Switching from Coal to Biomass Wood Chip in Circulating Fluidized Bed Boiler Habibi, Muhamad; Wicaksono, Sigit Tri
Spektra: Jurnal Fisika dan Aplikasinya Vol. 10 No. 1 (2025): SPEKTRA: Jurnal Fisika dan Aplikasinya, Volume 10 Issue 1, April 2025
Publisher : Program Studi Fisika Universitas Negeri Jakarta

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.21009/SPEKTRA.101.05

Presidential Regulation No. 112 of 2022 regulates the preparation of a road map to accelerate the termination of operating time for steam power plants (PLTU). Biomass’s potential to reduce emissions compared to coal explains why PLTU was chosen for this study. The operation of a PLTU requires the replacement of non-renewable electricity fuel sources with renewable ones. PLTUs are dominated by the use of coal. In accordance with presidential regulations, this research carried out fuel switching from coal to biomass. This research was conducted at PLTU Bolok, Kupang Regency. PLTU Bolok has a capacity of 2×16.5 MW. Fuel switching from coal to wood chip biomass in a Circulating Fluidized Bed (CFB) type boiler was carried out directly (direct co-firing), with five combustion treatments, namely, 100% coal and 0% biomass, 75% coal and 25% biomass, 50% coal and 50% biomass, 25% coal and 75% biomass and 0% coal and 100% biomass. The results of this research show that the performance of the biomass fuel switching caused the PLTU unit to experience a derating of 2 mW/hour. The results of other parameter analysis are FEGT 845.33 °C, furnace pressure -35 Pa and furnace temperature 947.04 °C. NOx emissions were reduced by 11.3 mg/Nm3, SO2 by 45.8 mg/Nm3 and CO2 12.5 mg/Nm3. The environmental benefit is the reduction emissions.

Coordinative Study of Organic Material on Silver Nanoparticles and Its Application for Colorimetric Sensor Rahayu, Setiya; Hidayah, Yoda Taruna; Syakuro, Qoid Abrori; Ronald, Azza Azahra; Herman; Wulandari, Priastuti
Spektra: Jurnal Fisika dan Aplikasinya Vol. 10 No. 1 (2025): SPEKTRA: Jurnal Fisika dan Aplikasinya, Volume 10 Issue 1, April 2025
Publisher : Program Studi Fisika Universitas Negeri Jakarta

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.21009/SPEKTRA.101.06

Metal nanoparticles, especially gold and silver nanoparticles, have been applied in various fields of nanotechnology because of their unique optical properties called localized surface plasmon resonance (LSPR). Metal nanoparticles need capping material to stabilize and protect the metal core. The interaction between capping and metal core affects the physical and chemical properties of metal nanoparticles. Silver nanoparticles have a robust extinction coefficient compared to other metals of the same size. In addition, silver nanoparticles have been found to have antimicrobial properties. There has been a lot of research on the coordination between organic molecules with silver metal. However, the study about the coordination between organic molecules on silver nanoparticles has not been studied in detail. For this reason, the synthesis of silver nanoparticles capped by citrate (AgCA) and silver nanoparticles capped by 3-MPA (AgMPA) was optimized in order to form stable colloids. The interaction between capping molecules (citrate and 3-MPA) and silver core was studied experimentally and computationally. In the results, some different vibration peak positions of chemical coordination between free carboxylate and the carboxylate on silver nanoparticles were found, indicating the effect of strong chemical bonding and the effect of localized surface plasmon. Agreement was found between the experimental results and the calculation based on DFT simulation, which shows the same tendencies of vibration peak position. Moreover, colorimetric testing with Biocytin-Avidin was performed as a sensor application in the experiment.

Non-Relativistic Quantum Particle Confined on a Cylindrical Surface under a Stark-like Potential Senjaya, Deriyan
Spektra: Jurnal Fisika dan Aplikasinya Vol. 10 No. 1 (2025): SPEKTRA: Jurnal Fisika dan Aplikasinya, Volume 10 Issue 1, April 2025
Publisher : Program Studi Fisika Universitas Negeri Jakarta

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.21009/SPEKTRA.101.04

This study explores the influence of a Stark-like perturbative potential on a quantum particle confined to a cylindrical surface (QPCS) and its implications for extra-dimensional theories. The QPCS framework is particularly relevant to Kaluza-Klein (KK) theory, which postulates extra spatial dimensions to unify electromagnetism and gravity. In KK theory, these extra dimensions are typically hidden and require high-energy conditions for detection. Motivated by the challenge of uncovering these dimensions more feasibly, this research applies a perturbative potential of the form ĤSL = βzV₀z(θ) to a QPCS characterized by length L and radius R₀. This potential is inspired by the Stark effect in hydrogen atoms, where energy level splitting serves as an indicator of an external influence. The study demonstrates that, for a degenerate configuration (R₀ = L/π), the Stark-like perturbation effectively induces energy level splitting, which can be interpreted as a means of revealing hidden dimensions. The first-order energy correction in this scenario depends explicitly on the quantum numbers nz and nθ, highlighting the potential for this approach to probe extra-dimensional effects in lower-energy quantum systems.

Theoretical Study of Positron-Electron Scattering with Thermal-Volkov Wavefunction KC, Narayan; Gupta, Suresh Prasad; Yadav, Kishroi; Dhobi, Saddam Husain
Spektra: Jurnal Fisika dan Aplikasinya Vol. 10 No. 2 (2025): SPEKTRA: Jurnal Fisika dan Aplikasinya, Volume 10 Issue 2, August 2025
Publisher : Program Studi Fisika Universitas Negeri Jakarta

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.21009/SPEKTRA.102.01

This study investigates the differential cross-section (DCS) for laser-assisted positron-electron scattering in a Gaussian wave packet, within a linearly polarized laser field in a thermal environment. For this, a theoretical model was developed with a designed thermal Gaussian Volkov wavefunction, vector potential, and scattering matrix with the application of the Bessel function. The developed model was computed using the Matlab programming language to study the nature of the developed model of DCS. The observation shows that the DCS initially increases with positron energy, reaching a peak around 0.5 eV; after that, it decreases with further increases in energy and approaches a constant at high energies. This is due to changing dynamics of positron-electron interactions with resonance occurring at specific energies. Also, the observation shows that temperature plays a significant role, especially at lower energies, with higher temperatures (325 K) enhancing the DCS due to increased thermal excitation of the target electrons. The study also explores the influence of the z-value and found that higher z-values lead to a decrease in the DCS due to the Coulombic interaction becoming stronger. Moreover, the effects of external factors such as the number of laser field photons and pulse duration are considered. The observation shows that shorter laser pulse durations and higher photon energies enhance the scattering process, while longer pulse durations result in a decrease in DCS. This study aids in optimizing technologies like PET imaging, plasma diagnostics, and particle accelerators by revealing how positron-electron scattering varies with energy, temperature, and laser parameters. It supports real-world applications in medical, space, and materials science.

Physicochemical and Mineralogical Characterization of Ciuyah Mud Volcano: Rare Earth Elements and Salt Minerals for the Advanced Materials Industry, Indonesia Nurfaradila, Fina; Agustine, Eleonora; Sartono; Nugroho, Amira Sasanti; Pranatikta, Krishna Agra
Spektra: Jurnal Fisika dan Aplikasinya Vol. 10 No. 2 (2025): SPEKTRA: Jurnal Fisika dan Aplikasinya, Volume 10 Issue 2, August 2025
Publisher : Program Studi Fisika Universitas Negeri Jakarta

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.21009/SPEKTRA.102.02

The Ciuyah Mud Volcano in West Java is a notable geological feature resulting from mud extrusion driven by subsurface pressure, buoyancy, and thermal variations. Its unique characteristics provide valuable insights into Earth's subsurface processes. Materials ejected from mud volcanoes often contain valuable minerals that are crucial for scientific investigation and economic application. Of particular interest at this site is the presence of Rare Earth Elements (REEs), which are vital for modern technology. The aim of this study is to provide a comprehensive characterisation of the Ciuyah Mud Volcano. The objectives are to: (1) determine its physicochemical properties using electrical conductivity (EC), volumetric water content (VWC), and total dissolved solids (TDS) measurements; (2) identify the distribution of REEs using X-Ray Fluorescence (XRF) and Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES); and (3) analyze the salt mineralogy using Scanning Electron Microscopy (SEM) and X-Ray Diffraction (XRD). The results revealed high conductivity in the mud, as evidenced by elevated EC and VWC values, as well as high TDS and salinity in the water samples. XRF and ICP-OES analyses confirmed the presence of twelve REEs: Ce, Dy, Eu, Gd, Ho, La, Nd, Pr, Sm, Tb, Sc, and Y. Furthermore, SEM and XRD identified Halite and Helvite as the primary salt minerals, characterized by large, hexagonal crystal structures. These findings highlight the potential of the Ciuyah Mud Volcano as a source of strategic REEs for Indonesia’s advanced materials and clean energy sectors, while also offering local socioeconomic applications, such as salt-based cosmetic products.

Analyzing the Influence of Bedrock Geometry on Ambient Vibration Using HVSR and Particle Dynamics Fazah, Hanum; Rosandi, Yudi
Spektra: Jurnal Fisika dan Aplikasinya Vol. 10 No. 2 (2025): SPEKTRA: Jurnal Fisika dan Aplikasinya, Volume 10 Issue 2, August 2025
Publisher : Program Studi Fisika Universitas Negeri Jakarta

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.21009/SPEKTRA.102.03

Ground vibration signals recorded by low-frequency multi-channel geophones provide information about the physical characteristics of a medium. Using the passive seismic method, vibrations are measured in three channels, i.e. horizontal and vertical directions. Since the characteristics of mediums, such as sediment thickness and soil hardness, are contained in low-amplitude ambient vibrations, further data selection is required to remove spikes in the signals induced by active sources. This work is necessary to reveal the characteristics that reflect the mediums’ physical condition from the signal. Conventionally, signal processing is based on the Horizontal-to-Vertical Signal Ratio (HVSR) calculation. The information obtained, such as sediment thickness and sub-surface shear velocity (Vs30), as well as the amplification factor and seismic vulnerability, are crucial for geotechnical applications. This data can be extracted from HVSR analysis. However, a complete understanding of the complex vibration signal shape related to the medium and local geological conditions is not fully understood. To gain a deeper understanding of the mechanism, numerical modeling is performed using a particle dynamics method. The vibration pattern of chosen particles on the surface was studied and its relation to the geometry of the fixed base region was investigated. The simulation results show systematic changes in signal form when processed with a similar HVSR method as a response to the shape of the fixed base.

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