物理最新文献

The exploration of archaeological heritage aims at understanding past societies through the study of ancient materials. While archaeometric analysis provides valuable insights, invasive sampling raises ethical concerns and is often restricted, necessitating the development of non-invasive techniques. This study presents a methodology based on X-Ray Diffraction using synchrotron radiation. The approach involves the elaboration and characterization of model alloys, with X-ray data analysis using Rietveld refinement and Williamson-Hall plot method. Phase identification along with crystallographical investigations conducted on three medieval armours provides insights into manufacturing techniques and highlights the method’s limitation.

In this manuscript, Hellmann-plus-Screened-Kratzer (HSK) potential is adopted as the heavy quark interaction potential for studying the thermodynamic properties of 1 S and 2 S states of heavy quarkonium (charmonium and bottomonium) using the Nikiforov-Uvarov functional analysis (NUFA) method. Initially, using this HSK potential, we have solved the Schrodinger equation in the presence of magnetic field-dependent quasi-particle Debye mass to get energy eigenvalue. Further, we have determined the partition function and the thermodynamic properties of quarkonia using energy eigenvalue. It is noted that as the magnetic field increases, the initial binding energy values are lower, although the general trend of decreasing binding energy with temperature remains consistent. The behavior of quarkonium states under extreme conditions sheds light on the impact of a strong magnetic field on their thermodynamic characteristics.

It is proved that charged thin shells (charged Dyson shells) can be supported in unstable static equilibrium states around spherically symmetric central compact objects. The regime of existence of the composed central-compact-object-static-charged-shell configurations is characterized by the inequalities (sqrt{m(m+2M)}<|q|<M+sqrt{M^2+m^2}), where ({m,q}) are respectively the proper mass and the electric charge of the supported shell and M is the mass of the central compact object (a black hole or an horizonless compact star). We reveal the physically interesting fact that the supported charged shells become marginally-stable in the (|q|/sqrt{m(m+2M)}rightarrow 1^+) limit, in which case the lifetime (instability timescale) of the composed system can be made arbitrarily large. Our analysis goes beyond the test shell approximation by properly taking into account the exact gravitational and electromagnetic self-interaction energies of the spherically symmetric shell in the curved spacetime. In particular, the existence of the composed compact-object-charged-shell static configurations in the Einstein–Maxwell theory is attributed to the non-linear electromagnetic self-energy of the supported shell.

Black hole (BH) mergers are natural sources of gravitational waves (GWs) and are possibly associated with electromagnetic events. Such events from a charged rotating BH with an accretion on to it could be more energetic and ultra-short-lived if the magnetic force dominates the accretion process because the attraction of ionized fluid with a strong magnetic field around the rotating BH further amplifies the acceleration of the charged particle via a gyromagnetic effect. Thus a stronger magnetic field and gravitational pull will provide an inward force to any fluid displaced in the radial direction and move it toward the axis of rotation with an increasing velocity. After many twists during rotation and the existence of restoring agents, Such events could produce a narrow intense jet starts in the form of Poynting flux along the axis of rotation resembling the Blandford–Znajek (BZ) mechanism. We investigated a charged rotating BH and obtained characteristic results (e.g., the remnant mass, magnetic field strength, luminosity, opening angle, viewing angle, and variation of viewing angle on the SGRB luminosity detection) that have a nice coincidence with rare events having GW associated with EM counterparts. This study gives a new insight into events with a strongly magnetized disk dominating the accretion process of energy extraction.

Classical electromagnetic radiation from moving point charges is foundational, but the thermal dynamics responsible for classical acceleration temperature are poorly understood. We investigate the thermal properties of classical electromagnetic radiation in the context of the correspondence between accelerated electrons and moving mirrors, focusing on three trajectories with asymptotically infinite (Davies–Fulling), asymptotically zero (Walker–Davies), and eternally uniform acceleration. The latter two are argued not to be thermal, while the former is found to emit thermal photons with a temperature that depends on the electron’s speed. Thermal radiation occurs in the absence of jerk.

Transmission optical absorption spectra of ion-irradiated 3C-SiC epitaxial films on a silicon substrate are measured in the visible-near infrared range from room temperature down to about 10 K. These data show strong interference fringe patterns on top of the silicon absorption edge at about 10,460 cm¹ which limits the transmittance of the samples. The radiation damage by 2.3-MeV Si⁺ and 3.0-MeV Kr⁺ ions is studied by following the impact of ion irradiation on these transmission spectra as a function of ion fluence and at various temperatures. The temperature dependence of the optical gap of silicon is deduced from the evolution of the fundamental absorption edge and that of the refractive index of SiC is deduced from the evolution of fringe spacing. The low temperature measurements evidence the shrinkage of band gap of silicon which is assigned to the gradual amorphization of the ion-implanted zone of the substrate as a function of fluence. These new results bridge a gap in the data on the properties of ion-induced damage in silicon carbide and silicon.

The configuration of a perfect fluid distribution in an electric field under the influence of higher curvature geometric effects introduced through the Gauss–Bonnet invariants is studied in the 4 dimensional Glavan–Lin gravity formulation. It is found that whereas a constant spatially directed gravitational potential gives isothermal behaviour in the standard theory, this is not the case when extra curvature is present in general. A physically viable stellar model is constructed by assuming the Finch–Skea potential. The geometry and electrodynamics are well behaved being regular throughout the distribution including the centre. The model passes stability tests such as the Chandrasekar adiabatic stability criterion and causality. Additionally all energy conditions are satisfied within the star. We compare the performance of the model with its Einstein counterpart and observe that the higher curvature exerts a notable influence on all the physical properties of the star.

Tin doped cadmium oxide (Cd_1-xSn_xO) thin films at different tin (Sn) concentrations (x = 0, 0.03, 0.05, 0.07) were prepared using electron beam evaporation technique and subjected to various characterisations. From XRD, prepared thin films shows polycrystalline nature with cubic structure. FE-SEM nano-graphs confirmed the elongated oval shape morphology with 1:3 aspect ratios. FT-IR analysis revealed the presence of functional groups and chemical interactions. Raman spectrum was recorded in the range of 200 cm⁻¹ to 1000 cm⁻¹. Using Tauc’s relation optical bandgap is calculated and it is found to be increased 2.00 eV – 2.40 eV. Photoluminescence spectra were recorded Cd_1-xSn_xO thin films and emission peaks were found in visible region. CIE diagrams confirm the thin films in blue- green portion. Using a source meter, the electrical properties were examined and it was observed that the electrical resistivity decreased. Magnetic properties reveals that the Sn-doped CdO thin films exhibit ferromagnetic nature.

In recent years, there has been a growing global interest in ultra-wide bandgap semiconductor materials, with aluminium nitride emerging as a particularly promising material. Using density-functional theory (DFT) at the CAM-B3LYP/6-311G(3d,2p) basis set level, we have systematically optimized the geometries of the (AlN)₁₂ cluster. Furthermore, the structural and thermodynamic changes of these clusters under the external electric field (EEF) were investigated. When the external electric field intensity increased the energy gap decreases continuously, infrared spectral analysis showed an obvious Stark effect, and the molecular structure showed significant alterations. Additionally, the study examined orbital compositions and excitation properties of twenty excited states using time-dependent density-functional theory (TD-DFT). The results indicated a decrease in excitation energy with increasing EEF, resulting in longer wavelengths and red-shifted spectral. These findings provide an opportunity to precisely modulate the electronic properties of (AlN)₁₂ cluster by controlling the strength and direction of the EEF, opening up more possibilities for their application in photoelectronic devices.

Graphical abstract

The focus of this paper is to investigate the behavior of a codimension-one thick brane in the modified symmetric teleparallel gravity structure (f(Q, {mathcal {T}})), where Q is the nonmetricity scalar and ({mathcal {T}}) is the trace of the energy–momentum tensor. Additionally, we examine whether braneworld scenarios are stable under small tensor perturbations and identify the associated massive and resonant modes. Our results indicate that the parameters controlling the modifications to the gravitational model-specifically those affecting nonmetricity and the energy–momentum tensor-significantly influence both the location and existence of these modes.