The Physics Society of IranIranian Journal of Physics Research1682-695725420260220A semi-analytical approach to the abundance of light elements in Big Bang nucleosynthesisA semi-analytical approach to the abundance of light elements in Big Bang nucleosynthesis391404374610.47176/ijpr.25.4.42095FASeyyed MohammadShahrokhiDepartment of Physics, Lorestan University, KhorramabadAhmadMohamadnejadDepartment of Physics, Lorestan University, Khorramabad0000-0002-9695-1999Journal Article20250427This paper presents a comprehensive semi-analytical approach to the temporal evolution and final abundance of light elements 7Be<strong> </strong> formed during Big Bang nucleosynthesis. By systematically examining the fundamental processes, we reveal the complex physics involved in the formation of these primordial elements. Our findings not only enhance the understanding of nucleosynthesis dynamics but also provide valuable insights into the conditions of the early universe and emphasize the importance of light elements in cosmic evolution. One of the most significant results of this paper is the derivation of semi-analytical relations for the final abundance of light elements as a function of the normalized baryon-to-photon ratio (η_10). In the end, the acceptable range of the parameter η_10 is discussed<strong> </strong>through a<strong> </strong>comparison of observational results.This paper presents a comprehensive semi-analytical approach to the temporal evolution and final abundance of light elements 7Be<strong> </strong> formed during Big Bang nucleosynthesis. By systematically examining the fundamental processes, we reveal the complex physics involved in the formation of these primordial elements. Our findings not only enhance the understanding of nucleosynthesis dynamics but also provide valuable insights into the conditions of the early universe and emphasize the importance of light elements in cosmic evolution. One of the most significant results of this paper is the derivation of semi-analytical relations for the final abundance of light elements as a function of the normalized baryon-to-photon ratio (η_10). In the end, the acceptable range of the parameter η_10 is discussed<strong> </strong>through a<strong> </strong>comparison of observational results.https://ijpr.iut.ac.ir/article_3746_e8542a04d734d0cae36d648b3f519e5c.pdfThe Physics Society of IranIranian Journal of Physics Research1682-695725420260220Synthesis and study of thermoluminescence and photoluminescence properties of dysprosium -doped alumina nanoparticles under gamma irradiationSynthesis and study of thermoluminescence and photoluminescence properties of dysprosium -doped alumina nanoparticles under gamma irradiation405413370110.47176/ijpr.25.4.22058FAMinaBagheriPhysics Department, University of Kashan, Kashan, IranEhsanSadeghi-Physics Department, University of Kashan, Kashan, Iran
-Institute of Nanoscience and Nanotechnology, University of Kashan, Kashan, IranMostafaZahedifar-Physics Department, University of Kashan, Kashan, Iran
-Institute of Nanoscience and Nanotechnology, University of Kashan, Kashan, IranJournal Article20250208This study investigates the dosimetric properties of alumina-based phosphor doped with dispersium impurity, evaluating its potential as highly sensitive thermoluminescent material for high-dose applications. All samples were synthesized using the sol-gel method. The highest sensitivity to gamma radiation from a 60Co source was observed in the sample with 0.5 mol% dispersium doping. The structural and morphological properties of the particles were examined using X-ray diffraction (XRD) and scanning electron microscopy (SEM), while elemental analysis of the α-alumina sample was analyzed using energy-dispersive X-ray spectroscopy (EDS). The kinetic parameters of the thermoluminescence (TL) glow curve were extracted through computer-based curve fitting. The TL glow curve exhibited two overlapping peaks at approximately 394 K and 449 K. Additional analyses of the glow curve characteristics, fading characteristics, and dose-response linearity demonstrated the strong potential of this nanophosphor as a high-sensitivity TL dosimeter suitable for high-dose radiation measurements.This study investigates the dosimetric properties of alumina-based phosphor doped with dispersium impurity, evaluating its potential as highly sensitive thermoluminescent material for high-dose applications. All samples were synthesized using the sol-gel method. The highest sensitivity to gamma radiation from a 60Co source was observed in the sample with 0.5 mol% dispersium doping. The structural and morphological properties of the particles were examined using X-ray diffraction (XRD) and scanning electron microscopy (SEM), while elemental analysis of the α-alumina sample was analyzed using energy-dispersive X-ray spectroscopy (EDS). The kinetic parameters of the thermoluminescence (TL) glow curve were extracted through computer-based curve fitting. The TL glow curve exhibited two overlapping peaks at approximately 394 K and 449 K. Additional analyses of the glow curve characteristics, fading characteristics, and dose-response linearity demonstrated the strong potential of this nanophosphor as a high-sensitivity TL dosimeter suitable for high-dose radiation measurements.https://ijpr.iut.ac.ir/article_3701_b181eaa49f5924e16c772dcb718fcd0f.pdfThe Physics Society of IranIranian Journal of Physics Research1682-695725420260220Trace of \Lambda(1405)in neutron momentum and energy spectra in Kstopped+d→πƩn eractionTrace of \Lambda(1405)in neutron momentum and energy spectra in Kstopped+d→πƩn eraction415423374710.47176/ijpr.25.4.42090FAJafarEsmailiDepartment of Physics, Faculty of Basic Sciences, Shahrekord University, Shahrekord, Iran0000-0001-9086-829XMohamadhoseinYaghoubi SurkiDepartment of Physics, Faculty of Basic Sciences, Shahrekord University, Shahrekord, IranJournal Article20250419In the present work, the effect of Lambda(1405) resonant state on the neutrons momentum and energy spectra due to a stopped kaon on deuteron is studied within the coupled-channel approach, employing Argonne V18SC potential to describe nucleon-nucleon interaction. For this purpose, both chiral and phenomenological potentials with different one-pole and two-pole structures have been used to investigate the dependence of the neutrons spectrum resulting from the interaction on the different models. In the following, using the Akaishi-Yamazaki model, we have shown that the Lambda(1405) resonance trace is clearly visible in such spectra. Our results indicate that a detailed study of the kaon–deuteron interaction can significantly contribute to improving our understanding of the KN-πƩ interaction and the nature of theresonance.In the present work, the effect of Lambda(1405) resonant state on the neutrons momentum and energy spectra due to a stopped kaon on deuteron is studied within the coupled-channel approach, employing Argonne V18SC potential to describe nucleon-nucleon interaction. For this purpose, both chiral and phenomenological potentials with different one-pole and two-pole structures have been used to investigate the dependence of the neutrons spectrum resulting from the interaction on the different models. In the following, using the Akaishi-Yamazaki model, we have shown that the Lambda(1405) resonance trace is clearly visible in such spectra. Our results indicate that a detailed study of the kaon–deuteron interaction can significantly contribute to improving our understanding of the KN-πƩ interaction and the nature of theresonance.https://ijpr.iut.ac.ir/article_3747_d8847be3f7cc1b14e9173908bebb2106.pdfThe Physics Society of IranIranian Journal of Physics Research1682-695725420260220The spectral form factor in Bosonic integrable systems with local random interactionsThe spectral form factor in Bosonic integrable systems with local random interactions423429374810.47176/ijpr.25.4.82162FAAliMollabashiSchool of Quantum Physics and Matter, Institute for Research in Fundamental Sciences (IPM)0000-0002-8192-1260SalehRahimi-KeshariSchool of Quantum Physics and Matter, Institute for Research in Fundamental Sciences (IPM)0000-0003-2108-7486Journal Article20250805The spectral form factor (SFF) is a widely used tool for diagnosing quantum chaos and information scrambling. Recent studies have shown that the SFF can also indicate scrambling behavior in integrable systems when non-local random couplings are present. In this work, we investigate integrable bosonic systems governed by quadratic Hamiltonians with local random interactions. Through numerical analysis, we demonstrate that the SFF exhibits a ramp at intermediate times, a feature absent in integrable systems without randomness. The presence of this ramp provides evidence supporting the notion of quantum information scrambling in locally coupled, yet integrable, systems.The spectral form factor (SFF) is a widely used tool for diagnosing quantum chaos and information scrambling. Recent studies have shown that the SFF can also indicate scrambling behavior in integrable systems when non-local random couplings are present. In this work, we investigate integrable bosonic systems governed by quadratic Hamiltonians with local random interactions. Through numerical analysis, we demonstrate that the SFF exhibits a ramp at intermediate times, a feature absent in integrable systems without randomness. The presence of this ramp provides evidence supporting the notion of quantum information scrambling in locally coupled, yet integrable, systems.https://ijpr.iut.ac.ir/article_3748_aaaccd2766ec67aecbe26459bb828d81.pdfThe Physics Society of IranIranian Journal of Physics Research1682-695725420260220Valley and spin transport and magnetoresistance in a borophene monolayerValley and spin transport and magnetoresistance in a borophene monolayer431441374910.47176/ijpr.25.4.52105FAHosseinGolfeshanInstitute of Nanoscience and Nanotechnology, University of Kashan, Kashan,IranNargesNikoofardInstitute of Nanoscience and Nanotechnology, University of Kashan, Kashan,Iran0000-0001-8623-3144HosseinNikoofardInstitute of Nanoscience and Nanotechnology, University of Kashan, Kashan,IranMahdiEsmailzadehIran University of Science and Technology, Tehran, IranJournal Article20250511In this paper, we investigate the spin and valley transport of electrons through a ferromagnet-normal-ferromagnet junction in a 8-pmmn borophene monolayer. A gate voltage is applied to the normal region and an exchange magnetic field is applied to both sides of this region through the ferromagnetic substrate. The exchange field breaks the spin degeneracy and results in spin polarization. On the other hand, the gate voltage induces valley polarization in the system. The valley polarization induced by the gate voltage is due to the presence of tilted and anisotropic Dirac cones in the borophene structure. While in materials such as graphene with isotropic cones, the gate voltage cannot induce valley polarization and strain must be applied to the system. Our proposed system can act as a perfect valley and spin filter such that the filtration characteristic can be controlled by changing the Fermi energy and gate voltage. It is observed that if the length of the normal region is greater than a certain limit, perfect valley polarization occurs. According to the results, this system can be used in borophene-based electronic and spintronic devices. The investigation of magnetoresistance is another study that has been conducted, and indicates the potential capability of this material in the fabrication of spin memories.In this paper, we investigate the spin and valley transport of electrons through a ferromagnet-normal-ferromagnet junction in a 8-pmmn borophene monolayer. A gate voltage is applied to the normal region and an exchange magnetic field is applied to both sides of this region through the ferromagnetic substrate. The exchange field breaks the spin degeneracy and results in spin polarization. On the other hand, the gate voltage induces valley polarization in the system. The valley polarization induced by the gate voltage is due to the presence of tilted and anisotropic Dirac cones in the borophene structure. While in materials such as graphene with isotropic cones, the gate voltage cannot induce valley polarization and strain must be applied to the system. Our proposed system can act as a perfect valley and spin filter such that the filtration characteristic can be controlled by changing the Fermi energy and gate voltage. It is observed that if the length of the normal region is greater than a certain limit, perfect valley polarization occurs. According to the results, this system can be used in borophene-based electronic and spintronic devices. The investigation of magnetoresistance is another study that has been conducted, and indicates the potential capability of this material in the fabrication of spin memories.https://ijpr.iut.ac.ir/article_3749_f9beb1e831faf6aaec2a5cecaf1af293.pdfThe Physics Society of IranIranian Journal of Physics Research1682-695725420260220Structural phase transformation mechanism of α-Fe under tensile loading at high strain rate: molecular dynamics studyStructural phase transformation mechanism of α-Fe under tensile loading at high strain rate: molecular dynamics study443450370210.47176/ijpr.25.4.82176FASeyed MehdiVaez AllaeiDepartment of Physics, University of Tehran0000-0002-4713-3818MohammadNourbakhshFaculty of Mechanical Engineering, Shahid Rajaee Teacher Training University0009-0008-7547-0871AliPourkamali AnarakiFaculty of Mechanical Engineering, Shahid Rajaee Teacher Training UniversityAyoubEsmailpourDepartment of Physics, Shahid Rajaee Teacher Training University0000-0001-8340-7348Journal Article20250821One of the most significant properties of metals is their ability to undergo phase transformations and structural changes in response to external forces, temperature variations, and other environmental factors. In this study, molecular dynamics (MD) simulations are employed to investigate phase transformation mechanisms and deformation behavior in a pristine and defect-free α-Fe specimen subjected to high strain rate tensile loading. The results reveal that, during the loading process, the microstructural transformation initiates from a body-centered cubic (bcc) structure to a face-centered cubic (fcc) structure, followed by a subsequent transition from fcc to a hexagonal close-packed (hcp) configuration. Furthermore, the critical stress levels follow the order stress(hcp)>stress(fcc)>stress(unknown)>stress(bcc), indicating that the hcp structure requires the highest stress to initiate transformation. Consequently, bond rupture and fracture nucleation are most likely to occur in the vicinity of this phase.One of the most significant properties of metals is their ability to undergo phase transformations and structural changes in response to external forces, temperature variations, and other environmental factors. In this study, molecular dynamics (MD) simulations are employed to investigate phase transformation mechanisms and deformation behavior in a pristine and defect-free α-Fe specimen subjected to high strain rate tensile loading. The results reveal that, during the loading process, the microstructural transformation initiates from a body-centered cubic (bcc) structure to a face-centered cubic (fcc) structure, followed by a subsequent transition from fcc to a hexagonal close-packed (hcp) configuration. Furthermore, the critical stress levels follow the order stress(hcp)>stress(fcc)>stress(unknown)>stress(bcc), indicating that the hcp structure requires the highest stress to initiate transformation. Consequently, bond rupture and fracture nucleation are most likely to occur in the vicinity of this phase.https://ijpr.iut.ac.ir/article_3702_a928731e103dfc64c0027fa84709689e.pdfThe Physics Society of IranIranian Journal of Physics Research1682-695725420260220Sequential coupling in plasmon–exciton–plasmon ternary nanoparticlesSequential coupling in plasmon–exciton–plasmon ternary nanoparticles451463375010.47176/ijpr.25.4.72136FAAbedAlemahmud ArdehaeiDepartment of Physics, Faculty of Science,University of QomEmadoddinYaghootiDepartment of Physics, Faculty of Science,University of QomFerydonBabaeiDepartment of Physics, Faculty of Science,University of QomJournal Article20250712In this study, the optical response of plasmon–exciton–plasmon (PEP) hybrid structures was investigated using the finite-difference time-domain (FDTD) simulation method. The structures were composed of disk-shaped metallic nanoparticles made of silver and gold, combined with molecular excitons originating from J-aggregated cyanine dyes. As an initial step, the extinction spectra of the individual metallic components and dye molecules were analyzed separately to identify the intrinsic resonance characteristics of each component. Subsequently, the influence of structural parameter variations on the coupling strength between the constituents was evaluated. The resulting spectra exhibited three distinct hybrid branches, namely the lower (L), middle (M), and upper (U) branches, indicating the interaction between the fundamental plasmonic and excitonic modes. By tracking the variations in detuning frequency, the coupling pathways between the plasmonic and excitonic resonances were identified.The results clearly demonstrate the pivotal role of nanoparticle size and detuning in Rabi splitting and the anti-crossing behavior of the hybrid modes. This study provides a comprehensive framework for spectral engineering of PEP hybrid structures and highlights their high potential for developing advanced nanophotonic devices and PEP-based biosensors.In this study, the optical response of plasmon–exciton–plasmon (PEP) hybrid structures was investigated using the finite-difference time-domain (FDTD) simulation method. The structures were composed of disk-shaped metallic nanoparticles made of silver and gold, combined with molecular excitons originating from J-aggregated cyanine dyes. As an initial step, the extinction spectra of the individual metallic components and dye molecules were analyzed separately to identify the intrinsic resonance characteristics of each component. Subsequently, the influence of structural parameter variations on the coupling strength between the constituents was evaluated. The resulting spectra exhibited three distinct hybrid branches, namely the lower (L), middle (M), and upper (U) branches, indicating the interaction between the fundamental plasmonic and excitonic modes. By tracking the variations in detuning frequency, the coupling pathways between the plasmonic and excitonic resonances were identified.The results clearly demonstrate the pivotal role of nanoparticle size and detuning in Rabi splitting and the anti-crossing behavior of the hybrid modes. This study provides a comprehensive framework for spectral engineering of PEP hybrid structures and highlights their high potential for developing advanced nanophotonic devices and PEP-based biosensors.https://ijpr.iut.ac.ir/article_3750_685ac8cadc1be5ac98da9556bc1c8d9e.pdfThe Physics Society of IranIranian Journal of Physics Research1682-695725420260220Tunable broadband perfect absorber based on GrapheneTunable broadband perfect absorber based on Graphene465469371110.47176/ijpr.25.4.12280FARaminJoudiDepartment of Physics, University of Zanjan, IranMojtabaNasiriDepartment of Physics, University of Zanjan, Iran0000-0003-2208-8528EbrahimMadadiFaculty of Engineering Sciences and Engineering Physics, Buin ZahraJournal Article20250807In this paper a graphene-based metasurface is designed and analyzed to operate as an electromagnetic wave absorber in the terahertz frequency range. The proposed geometrical structure consists of a graphene ring with four slits in each unit cell, arranged in a two-dimensional array on a dielectric substrate. Simulation results obtained using the finite element method (FEM) demonstrate that, by tuning the geometric and physical parameters of the structure—such as the slit width inner and outer radii of the ring and the Fermi energy of graphene—the absorption of electromagnetic waves can be significantly enhanced over a specific frequency range. This high absorption performance is attributed to the excitation of surface plasmon resonances in graphene as well as the induced magnetic resonance modes within the ring structure. The proposed design offers high tunability and fabrication simplicity, making it a promising candidate for applications in terahertz sensing tunable absorbers and stealth technologies.In this paper a graphene-based metasurface is designed and analyzed to operate as an electromagnetic wave absorber in the terahertz frequency range. The proposed geometrical structure consists of a graphene ring with four slits in each unit cell, arranged in a two-dimensional array on a dielectric substrate. Simulation results obtained using the finite element method (FEM) demonstrate that, by tuning the geometric and physical parameters of the structure—such as the slit width inner and outer radii of the ring and the Fermi energy of graphene—the absorption of electromagnetic waves can be significantly enhanced over a specific frequency range. This high absorption performance is attributed to the excitation of surface plasmon resonances in graphene as well as the induced magnetic resonance modes within the ring structure. The proposed design offers high tunability and fabrication simplicity, making it a promising candidate for applications in terahertz sensing tunable absorbers and stealth technologies.https://ijpr.iut.ac.ir/article_3711_aba18772fc70c8cbf79a79f413ef102b.pdfThe Physics Society of IranIranian Journal of Physics Research1682-695725420260220Growth and characterization of potassium dihydrogen phosphate (KDP) single crystal and feasibility of second harmonic generation of Nd:YAG laserGrowth and characterization of potassium dihydrogen phosphate (KDP) single crystal and feasibility of second harmonic generation of Nd:YAG laser471479375110.47176/ijpr.25.4.42097FAHadisCheraghiFaculty of Applied Sciences, Malek Ashtar University of Technology, IranMajidAghababagoliFaculty of Applied Sciences, Malek Ashtar University of Technology, IranMohsenYazdanmehrFaculty of Applied Sciences, Malek Ashtar University of Technology, Iran0000-0001-5570-9525HassanAhmadvandFaculty of Applied Sciences, Malek Ashtar University of Technology, IranJournal Article20250428Second harmonic generation (SHG) in solid-state lasers is always a significant aspect of nonlinear optics, achievable through certain single crystals such as potassium dihydrogen phosphate (KDP). In this study, the KDP single crystal was grown by the solution growth method using solvent evaporation at a constant temperature of 45°C, employing accurate temperature control and stabilization equipment. The grown single crystal was oriented using the X-ray Laue diffraction method, confirming its single-crystalline nature. The X-ray diffraction (XRD) analysis verified the crystalline phase formation and the absence of secondary phases in the crushed crystal sample. Fourier transform infrared (FTIR) spectroscopy confirmed the presence of bending, stretching, and other bonds. Diffuse reflectance spectroscopy (DRS) measurements yielded a bandgap of 4.12 eV for the grown crystal. The transmission spectrum demonstrated high transparency (>45%) in the 200–800 nm wavelength range. The optical axis and phase-matching angle of the grown crystal were determined based on Laue diffraction patterns, after which the crystal was rotated using a goniometer and sliced. Finally, second harmonic generation was tested using a 1064 nm Nd:YAG laser, successfully producing green light output at 532 nm.Second harmonic generation (SHG) in solid-state lasers is always a significant aspect of nonlinear optics, achievable through certain single crystals such as potassium dihydrogen phosphate (KDP). In this study, the KDP single crystal was grown by the solution growth method using solvent evaporation at a constant temperature of 45°C, employing accurate temperature control and stabilization equipment. The grown single crystal was oriented using the X-ray Laue diffraction method, confirming its single-crystalline nature. The X-ray diffraction (XRD) analysis verified the crystalline phase formation and the absence of secondary phases in the crushed crystal sample. Fourier transform infrared (FTIR) spectroscopy confirmed the presence of bending, stretching, and other bonds. Diffuse reflectance spectroscopy (DRS) measurements yielded a bandgap of 4.12 eV for the grown crystal. The transmission spectrum demonstrated high transparency (>45%) in the 200–800 nm wavelength range. The optical axis and phase-matching angle of the grown crystal were determined based on Laue diffraction patterns, after which the crystal was rotated using a goniometer and sliced. Finally, second harmonic generation was tested using a 1064 nm Nd:YAG laser, successfully producing green light output at 532 nm.https://ijpr.iut.ac.ir/article_3751_21ce689121e39821d07d04faab328370.pdfThe Physics Society of IranIranian Journal of Physics Research1682-695725420260220Computational search and investigation of structural phases of Aluminum-Carbon alloyComputational search and investigation of structural phases of Aluminum-Carbon alloy481489375210.47176/ijpr.25.4.82167FARezaShahsavariDepartment of Mechanical Engineering, Isfahan University of TechnologySeyed JavadHashemifarDepartment of Physics, Isfahan University of Technology0000-0002-2589-8772GillesFrapperApplied Quantum Chemistry Group, E4 team, IC2MP UMR 7285, Université de Poitiers – CNRS, 4, rue Michel Brunet TSA 51106-86073, Poitiers, FranceJournal Article20250810In this study, we employed an evolutionary algorithm and density functional theory (DFT) calculations to identify stable and metastable structural phases of aluminum-carbon compounds. Initially, a variable - composition structure search was conducted at ambient pressure to determine the convex hull of the system. Subsequently, we performed a fixed - composition structure search for alloys located on this convex hull, along with some neighboring alloys to identify their stable and metastable structural phases. Along with the most stable phase, seven metastable phases were chosen from this set, and their phonon, mechanical, and electronic properties were determined using DFT calculations. The phonon dispersion calculations reveal that all eight chosen structures are dynamically stable. A comparison of the mechanical properties of these structures reveals a novel and extremely hard phase in the aluminum-carbon alloy, which can be synthesized in thin-film form or utilized in high-temperature operating conditions. First-principles electronic structure calculations reveal that surface carbon doping in the Al-C system enables tunable metallic conductivity while maintaining an exceptional hardness-to-weight ratio.In this study, we employed an evolutionary algorithm and density functional theory (DFT) calculations to identify stable and metastable structural phases of aluminum-carbon compounds. Initially, a variable - composition structure search was conducted at ambient pressure to determine the convex hull of the system. Subsequently, we performed a fixed - composition structure search for alloys located on this convex hull, along with some neighboring alloys to identify their stable and metastable structural phases. Along with the most stable phase, seven metastable phases were chosen from this set, and their phonon, mechanical, and electronic properties were determined using DFT calculations. The phonon dispersion calculations reveal that all eight chosen structures are dynamically stable. A comparison of the mechanical properties of these structures reveals a novel and extremely hard phase in the aluminum-carbon alloy, which can be synthesized in thin-film form or utilized in high-temperature operating conditions. First-principles electronic structure calculations reveal that surface carbon doping in the Al-C system enables tunable metallic conductivity while maintaining an exceptional hardness-to-weight ratio.https://ijpr.iut.ac.ir/article_3752_48df7b8e8d586a55cf3e7054a4c85b30.pdfThe Physics Society of IranIranian Journal of Physics Research1682-695725420260220Ethanol gas sensing with single-layer fluorinated graphene in ohmic and transistor junctionsEthanol gas sensing with single-layer fluorinated graphene in ohmic and transistor junctions491507372710.47176/ijpr.25.4.82157FAAsieh SadatKazemiDepartment of Physics, Iran University of Science and Technology, Tehran, Iran0000-0003-4205-6232MobinaBolhasaniDepartment of Physics, Iran University of Science and Technology, Tehran, Iran, Seyed Mohamad AminTabatabaeeDepartment of Physics, Iran University of Science and Technology, Tehran, IranJournal Article20250803Graphene, a two-dimensional carbon material with properties such as high cross-sectional area and excellent electrical conductivity, has wide applications in the manufacture of volatile organic compound (VOC) sensors. These sensors allow the detection and measurement of these compounds by changing the electrical properties of graphene upon exposure to VOC molecules. Such sensors are of great importance in air quality and environmental monitoring. In this study, a monolayer graphene-silicon junction-based sensor was fabricated using photolithography and graphene wet transfer. To enhance the performance, the graphene sheet was converted into semiconducting fluorinated graphene using SF<sub>6</sub> plasma, and then, the performance of this sensor in detecting ethanol gas was evaluated in both ohmic and transistor modes. The surface characterization of this sensor was carried out using various methods such as scanning electron microscopy and atomic force microscopy, and the effects of fluorination on graphene were also investigated through, Energy-dispersive X-ray spectroscopy, Raman spectroscopy, and attenuated total reflectance spectroscopies. Finally, the sensor performance was evaluated by measuring the current-voltage changes in the presence of ethanol gas. In terms of the mechanism of action, the adsorption of ethanol on the surface of the semiconducting fluorinated graphene leads to electron donation and an increase in the number of charge carriers. These electrical changes are the basis of the sensor performance for ethanol detection. The results show that the saturation limit is reduced by applying a gate voltage compared to the ohmic junctions, and this value becomes even lower with increasing ethanol concentration. Overall, the sensing performance in the transistor mode was better than that of the ohmic one. The development of a new generation of graphene-based VOC sensors will play a vital role in air pollution monitoring due to their high response speed, excellent sensitivity, and surface modification capabilities.Graphene, a two-dimensional carbon material with properties such as high cross-sectional area and excellent electrical conductivity, has wide applications in the manufacture of volatile organic compound (VOC) sensors. These sensors allow the detection and measurement of these compounds by changing the electrical properties of graphene upon exposure to VOC molecules. Such sensors are of great importance in air quality and environmental monitoring. In this study, a monolayer graphene-silicon junction-based sensor was fabricated using photolithography and graphene wet transfer. To enhance the performance, the graphene sheet was converted into semiconducting fluorinated graphene using SF<sub>6</sub> plasma, and then, the performance of this sensor in detecting ethanol gas was evaluated in both ohmic and transistor modes. The surface characterization of this sensor was carried out using various methods such as scanning electron microscopy and atomic force microscopy, and the effects of fluorination on graphene were also investigated through, Energy-dispersive X-ray spectroscopy, Raman spectroscopy, and attenuated total reflectance spectroscopies. Finally, the sensor performance was evaluated by measuring the current-voltage changes in the presence of ethanol gas. In terms of the mechanism of action, the adsorption of ethanol on the surface of the semiconducting fluorinated graphene leads to electron donation and an increase in the number of charge carriers. These electrical changes are the basis of the sensor performance for ethanol detection. The results show that the saturation limit is reduced by applying a gate voltage compared to the ohmic junctions, and this value becomes even lower with increasing ethanol concentration. Overall, the sensing performance in the transistor mode was better than that of the ohmic one. The development of a new generation of graphene-based VOC sensors will play a vital role in air pollution monitoring due to their high response speed, excellent sensitivity, and surface modification capabilities.https://ijpr.iut.ac.ir/article_3727_d3802b1dc0d80d8a3c8ccc6ccc068e7c.pdfThe Physics Society of IranIranian Journal of Physics Research1682-695725420260220Phonon-mediated spin Seebeck effect in magnetic insulator heterostructuresPhonon-mediated spin Seebeck effect in magnetic insulator heterostructures509516375410.47176/ijpr.25.4.72146FAMajidShirdel-HavarPhysics Department/ Iran University of Science and TechnologyBabakZarePhysics Department/ Iran University of Science and TechnologyJournal Article20250724The spin Seebeck effect is investigated in a symmetric multilayer structure consisting of two ferromagnetic insulator layers separated by a nonmagnetic insulating spacer under an applied temperature gradient. Nonlocal spin transport between the two magnetic layers is mediated by phonons excited through magnetoelastic interaction and magnetization dynamics. The results show that the generated spin current is dependent on the geometric dimensions of the structure, exhibiting an oscillatory behavior with gradual attenuation as the thickness of the non-magnetic layer increases, and a resonant behavior with respect to the thickness of the magnetic layers. Furthermore, the spin transport mediated by phonons can persist over distances ranging from several hundred micrometers to millimeters in this structure.The spin Seebeck effect is investigated in a symmetric multilayer structure consisting of two ferromagnetic insulator layers separated by a nonmagnetic insulating spacer under an applied temperature gradient. Nonlocal spin transport between the two magnetic layers is mediated by phonons excited through magnetoelastic interaction and magnetization dynamics. The results show that the generated spin current is dependent on the geometric dimensions of the structure, exhibiting an oscillatory behavior with gradual attenuation as the thickness of the non-magnetic layer increases, and a resonant behavior with respect to the thickness of the magnetic layers. Furthermore, the spin transport mediated by phonons can persist over distances ranging from several hundred micrometers to millimeters in this structure.https://ijpr.iut.ac.ir/article_3754_2e3d2c4f33a7a1f58bc6c81cacd21e9c.pdfThe Physics Society of IranIranian Journal of Physics Research1682-695725420260220Design of a passband optical filter in a one-dimensional photonic crystal based on a reconfigurable Sb2S3 nanodefectDesign of a passband optical filter in a one-dimensional photonic crystal based on a reconfigurable Sb2S3 nanodefect517535375510.47176/ijpr.25.4.82168FAZahraEhsanianDepartment of Atomic and Molecular Physics, Faculty of Science, University of Mazandaran, Babolsar, IranArezouRashidiDepartment of Atomic and Molecular Physics, Faculty of Science, University of Mazandaran, Babolsar, Iran0000-0001-5944-3226Journal Article20250811In this article, the optical response of a symmetric one-dimensional photonic crystal incorporating a central defect layer of Sb₂S₃ nanomaterial in the near-infrared region is simulated and analyzed using the transfer matrix method. The effects of the amorphous-to-crystalline phase transition of the defect layer, as well as variations in the incident angle of the incoming light, on the transmission characteristics of the structure in both TE and TM polarizations are investigated. The results show that the amorphous-to-crystalline phase transition of Sb₂S₃ induces a pronounced red shift in the defect mode wavelength, whereas increasing the incidence angle leads to a blue shift of both the photonic bandgap and the defect mode in both polarizations. For TE polarization, the defect mode linewidth decreases with increasing angle, resulting in a higher quality factor; however, for TM polarization, at angles close to the Brewster angle, the defect mode merges with the bandgap edge, leading to a degradation of the filter performance. The analysis of the transmittance difference between the two phases further reveals the high angular and polarization sensitivity of the structure. These findings confirm the strong potential of Sb₂S₃ for the design of angle-sensitive optical filters and reconfigurable photonic devices with spectral switching and modulation capabilities.In this article, the optical response of a symmetric one-dimensional photonic crystal incorporating a central defect layer of Sb₂S₃ nanomaterial in the near-infrared region is simulated and analyzed using the transfer matrix method. The effects of the amorphous-to-crystalline phase transition of the defect layer, as well as variations in the incident angle of the incoming light, on the transmission characteristics of the structure in both TE and TM polarizations are investigated. The results show that the amorphous-to-crystalline phase transition of Sb₂S₃ induces a pronounced red shift in the defect mode wavelength, whereas increasing the incidence angle leads to a blue shift of both the photonic bandgap and the defect mode in both polarizations. For TE polarization, the defect mode linewidth decreases with increasing angle, resulting in a higher quality factor; however, for TM polarization, at angles close to the Brewster angle, the defect mode merges with the bandgap edge, leading to a degradation of the filter performance. The analysis of the transmittance difference between the two phases further reveals the high angular and polarization sensitivity of the structure. These findings confirm the strong potential of Sb₂S₃ for the design of angle-sensitive optical filters and reconfigurable photonic devices with spectral switching and modulation capabilities.https://ijpr.iut.ac.ir/article_3755_cd3bbc2d7ca1bbdc055acf58609e6c24.pdfThe Physics Society of IranIranian Journal of Physics Research1682-695725420260220The influence of polarization angle on plasmonic and thermoplasmonic properties of star-shaped nanoframes for use in photothermal therapyThe influence of polarization angle on plasmonic and thermoplasmonic properties of star-shaped nanoframes for use in photothermal therapy543537375610.47176/ijpr.25.4.62116FAAbbasAzarianDepartment of Physics, University of Qom, Qom, Iran0000-0003-2365-6224ShaghayeghZamaninajafabadiDepartment of Physics, University of Qom, Qom, Iran0009-0007-4118-8328Journal Article20250602In this study, the influence of the polarization angle on the plasmonics and thermoplasmonics properties of star-shaped gold dimer nanoframes (SGDNs) with five branches is investigated using the finite-difference time-domain (FDTD) method. Notably, varying the polarization angle shifts the first localized surface plasmon resonance (LSPR) peak, while the second plasmonic mode remains unaffected. This asymmetry arises from the anisotropic geometry of the SGDNs. The simulation results show that for light polarization parallel to the dimer axis, the SGDNs can increase the local electric field up to 117 times, and the highest temperature change in the SGDNs, with a value of ΔTmax=140°C, is observed under this light polarization. Also, λ=1800 nm for the SGDNs is identified as an isosbestic point, which is independent of illumination polarization, and this characteristic can be utilized in photothermal therapy.In this study, the influence of the polarization angle on the plasmonics and thermoplasmonics properties of star-shaped gold dimer nanoframes (SGDNs) with five branches is investigated using the finite-difference time-domain (FDTD) method. Notably, varying the polarization angle shifts the first localized surface plasmon resonance (LSPR) peak, while the second plasmonic mode remains unaffected. This asymmetry arises from the anisotropic geometry of the SGDNs. The simulation results show that for light polarization parallel to the dimer axis, the SGDNs can increase the local electric field up to 117 times, and the highest temperature change in the SGDNs, with a value of ΔTmax=140°C, is observed under this light polarization. Also, λ=1800 nm for the SGDNs is identified as an isosbestic point, which is independent of illumination polarization, and this characteristic can be utilized in photothermal therapy.https://ijpr.iut.ac.ir/article_3756_91f9fec9b080c74297a55c392b5f40a4.pdfThe Physics Society of IranIranian Journal of Physics Research1682-695725420260220Design and simulation of a microwave free electron laser based on a low-energy Dynamitron electrostatic acceleratorDesign and simulation of a microwave free electron laser based on a low-energy Dynamitron electrostatic accelerator545551375710.47176/ijpr.25.4.82179FAAfzalRaghaviDepartment of Physics- Basic sciences faculty- Payame Noor University- Tehran- Iran0000-0002-2649-3961Journal Article20250825In this paper, the possibility of constructing a free electron laser based on the electron beam from a Dynamitron accelerator manufactured by the Atomic Energy Organization of Iran has been studied. This study is conducted through theoretical analysis and computer simulation. The results show that if this accelerator is upgraded to deliver, at the same energy, an output current of at least 1 A, it can be used as the electron source of an oscillator-type free electron laser with an output of the order of 1 kW in the microwave region.In this paper, the possibility of constructing a free electron laser based on the electron beam from a Dynamitron accelerator manufactured by the Atomic Energy Organization of Iran has been studied. This study is conducted through theoretical analysis and computer simulation. The results show that if this accelerator is upgraded to deliver, at the same energy, an output current of at least 1 A, it can be used as the electron source of an oscillator-type free electron laser with an output of the order of 1 kW in the microwave region.https://ijpr.iut.ac.ir/article_3757_b4affa4f6b27df047d63d66fe4ac5600.pdfThe Physics Society of IranIranian Journal of Physics Research1682-695725420260220Design of a strip silicon waveguide and its optical characteristicsDesign of a strip silicon waveguide and its optical characteristics553563371210.47176/ijpr.25.4.82183FAFatemehMahmoudiradDepartment of Nanotechnology, Graduate University of Advanced Technology, Kerman, IranAbolfazlSafaei BezgabadiDepartment of Nanotechnology, Graduate University of Advanced Technology, Kerman, Iran0000-0003-2772-946XHamid RezaBakhtiarizadehDepartment of Nanotechnology, Graduate University of Advanced Technology, Kerman, Iran0000-0001-7065-0082Journal Article20250829Due to the significant advancements in silicon photonics, this paper presents a design of a strip silicon waveguide using COMSOL software, and its optical characteristics are simulated. The results show that this waveguide has two propagating modes, Transverse Electric (TE) mode and one Transverse Magnetic (TM) mode. The electric field profiles for these modes are illustrated at specific wavelengths. In addition, the effective refractive index, waveguide dispersion, and effective mode area have been investigated. For the proposed structure, the effective refractive index of the TM mode is always greater than that of the TE mode. Both modes have a zero dispersion wavelength over the examined wavelength range, occurring around 2.5 μm for the TM mode and approximately 2.12 μm for the TE mode. Our findings show that the effective mode area of both modes is on the order of 0.1 μm<sup>2</sup> and does not increase much with increasing wavelength. Furthermore, the effective mode area for the TE mode first increases and then decreases. Finally, by utilizing the equations governing the supercontinuum generation process in silicon waveguides, this process is studied in the proposed waveguide. The simulation results indicate that, depending on the characteristics of the injected pulse, the output from the waveguide achieves a spectral broadening of one octave.Due to the significant advancements in silicon photonics, this paper presents a design of a strip silicon waveguide using COMSOL software, and its optical characteristics are simulated. The results show that this waveguide has two propagating modes, Transverse Electric (TE) mode and one Transverse Magnetic (TM) mode. The electric field profiles for these modes are illustrated at specific wavelengths. In addition, the effective refractive index, waveguide dispersion, and effective mode area have been investigated. For the proposed structure, the effective refractive index of the TM mode is always greater than that of the TE mode. Both modes have a zero dispersion wavelength over the examined wavelength range, occurring around 2.5 μm for the TM mode and approximately 2.12 μm for the TE mode. Our findings show that the effective mode area of both modes is on the order of 0.1 μm<sup>2</sup> and does not increase much with increasing wavelength. Furthermore, the effective mode area for the TE mode first increases and then decreases. Finally, by utilizing the equations governing the supercontinuum generation process in silicon waveguides, this process is studied in the proposed waveguide. The simulation results indicate that, depending on the characteristics of the injected pulse, the output from the waveguide achieves a spectral broadening of one octave.https://ijpr.iut.ac.ir/article_3712_87ae6fb631f7c8a627e8e28785d9992d.pdfThe Physics Society of IranIranian Journal of Physics Research1682-695725420260220The role of sequence-dependent energy landscape in the formation of nucleosome-depleted regionsThe role of sequence-dependent energy landscape in the formation of nucleosome-depleted regions565574375910.47176/ijpr.25.4.72137FAMahshidHabibiInstitute for Advanced Studies in Basic Sciences, Zanjan, IranFarshidMohammad-RafieeInstitute for Advanced Studies in Basic Sciences, Zanjan, IranJournal Article20250713The nucleosome-depleted region is a part of the genome that serves as a binding site for key components of the transcriptional machinery, including RNA polymerase, transcription factors, motor proteins, and other essential cellular regulators. Occupation of this region by nucleosomes can disrupt proper transcriptional function. The sequence-dependent mechanical properties of DNA strongly influence nucleosome positioning along the genome. In this study, we present a stochastic model based on the sequence-dependent energy landscape to simulate the diffusive motion of nucleosomes along DNA. Using the Gillespie algorithm, we model the dynamics of nucleosomes along a 901-base-pair DNA segment and compute the nucleosome occupancy profile. The results show that high-energy regions act as physical barriers to nucleosome formation, leading to the emergence of NDRs. Moreover, the energy landscape of the adjacent regions plays a crucial role in the formation of NDRs and the overall distribution of nucleosomes. From the simulations, we can see a natural pattern in how nucleosomes are positioned around these NDRs. This model provides a theoretical framework for improving our understanding of chromatin organization both in vitro and in vivo.The nucleosome-depleted region is a part of the genome that serves as a binding site for key components of the transcriptional machinery, including RNA polymerase, transcription factors, motor proteins, and other essential cellular regulators. Occupation of this region by nucleosomes can disrupt proper transcriptional function. The sequence-dependent mechanical properties of DNA strongly influence nucleosome positioning along the genome. In this study, we present a stochastic model based on the sequence-dependent energy landscape to simulate the diffusive motion of nucleosomes along DNA. Using the Gillespie algorithm, we model the dynamics of nucleosomes along a 901-base-pair DNA segment and compute the nucleosome occupancy profile. The results show that high-energy regions act as physical barriers to nucleosome formation, leading to the emergence of NDRs. Moreover, the energy landscape of the adjacent regions plays a crucial role in the formation of NDRs and the overall distribution of nucleosomes. From the simulations, we can see a natural pattern in how nucleosomes are positioned around these NDRs. This model provides a theoretical framework for improving our understanding of chromatin organization both in vitro and in vivo.https://ijpr.iut.ac.ir/article_3759_cbf22ab286e2ad4900bdf5d6a2e47009.pdf