物理最新文献

Pulsed laser ablation is an increasingly prevalent method for fast ion trap loading of various species, however characteristics of the ablation target source material can affect the ion-loading process. One factor which can reduce the atomic flux from a target is oxidation during atmospheric exposure when preparing or making changes to the ion trap vacuum system. Recent work has shown that perovskite ablation targets produce consistent atomic densities even after exposure to atmosphere when compared to elemental source targets. In this work, we directly compare calcium (Ca) and calcium-titanate (CaTiO(_3)) ablation targets, characterizing the neutral atomic beam flux using resonant, time-resolved absorption spectroscopy of the 423 nm ¹S₀ (rightarrow) ¹P₁ transition in neutral Ca. We measure the ablation plume longitudinal and transverse temperatures, number density, ion production, and spot lifetime for each target. In addition, we compare the probe laser beam absorption for both targets before and after 21-h of exposure to atmosphere, demonstrating the relative robustness of the CaTiO(_3) source.

In the present article, we have imagined a hypothetical spherically symmetric stellar structure, made by an isotropic fluid satisfying dark energy equation of sate (EOS), named as dark energy star (DES), in the context of gravity’s rainbow. We adopted modified Chaplygin gas EOS with an extra parameter (alpha ) satisfying (0le alpha le 1). In a recent literature Tudeshki et al. (Phys. Lett. B 848 (2024) 138333) investigated the same type stellar configuration, including the mass-radius relation for (alpha =1). However, we have investigated the effect of the rainbow function on such hypothetical DESs corresponding to (alpha =0.8~text {and}~0.9). Mainly, we have concentrated on two features like, mass-radius relation and radial oscillations in the effect of rainbow function. After computing the values of maximum mass and corresponding radius of the star, we compared our results with GR and some chosen observed relativistic stellar candidates. Moreover, we have computed the frequencies and shown the behavior of corresponding Eigenfunctions for the six lowest excited modes in the variation of the rainbow function. As a final result, we have our proposed stellar structure is physically reasonable and may be placed in the ‘mass-gap’ region corresponding to some fixed values of model parameters.

Sprayed thin coatings of tin sulphide (SnS) onto glass substrates utilizing tin chloride dehydrate and CS (NH₂)₂ as precursors, in various substrate temperatures (250–325 °C) in steps of 25 °C. The physical properties were studied for all the as prepared SnS thin films. The increased substrate temperature on the film shows the increased crystallinity along orthorhombic nature of (040) plane. The Debye-Scherer formula was used to determine the crystallite’s size, which ranged from 20 to 29 nm. The morphological, energy-dispersive X-ray spectroscopy (EDS) and 3D AFM micrographs were characterized to find the morphology and surface roughness of thin film. Optical transmittance spectra (500 nm–1100 nm) revealed that all films had direct band gap values with appropriate range of photo voltaic applications. In the FT-IR spectrum’s absorption band, the characteristic stretching vibration mode of SnS thin films were analysed. The film developed at 325 °C had the lowest electrical resistivity of 4.28 Ω cm with a hole concentration of around 10¹³ cm⁻³. As the temperature of growth of the thin film increased, the resistance rapidly reduced.

Interfering radiation, such as self-emitting thermal radiation, infrared radiation from heating sources, and combustion gas radiation, significantly impacts the use of optical thermometry. How to improve the precision of temperature measurement in such an environment is a key issue. Therefore, this work aimed to quantitatively analyze the temperature measurement precision of luminescence lifetime thermometry for measuring the temperatures of hot components in environments with interfering radiation. In this paper, based on the quantitative analysis of measurement noise of optical signal and the error propagation theory, we proposed a theoretical model for predicting the temperature measurement precision of luminescence lifetime thermometry. Using blue LED as the interfering radiation source, the temperature measurement experiments of high-temperature surfaces under different interfering radiation intensities were carried out. By comparing the measured precision based on the standard deviation of repeated experiments with the predicted precision of the theoretical model proposed in this paper, the reliability of this theoretical model was verified. The experiments also revealed that the temperature measurement precision was linearly related to the square root of the measured signal intensity (i.e., the sum of luminescence signal and interfering radiation signal). With the increase of the background interfering radiation intensity, although the accuracy of temperature measurement did not change significantly, the measurement noise increases, resulting in a significant increase in random error of measured temperature. This work provides guidance for developing luminescence lifetime thermometers and their applications in environments with interfering radiation.

Social networks have become the best medium for the unbridled dissemination of rumor, which arises with the crisis of environment and has serious negative functions on social stability and people’s daily life. At present, a series of models have been constructed to study the spreading dynamics of rumor. However, most of existing researches ignore the competitive relationships between rumor and anti-rumor, and the emotional tendencies that may occurs during the propagation process of rumor. In this work, we construct a Susceptible-Exposed-Infectious-Debunker-Recovered (SEIDR) model by adopting the emotional infection theory of users and the competitive mechanism between rumor and anti-rumor. Furthermore, we investigate the influence of debunking behaviors and varying emotional intensities on the propagation of rumor. Then, the stability behaviors of rumor-free and epidemic equilibriums are calculated according to Routh–Hurwitz stability criterion. Finally, numerical examples are carried out to describe the influence of different parameters and verify the validity of theoretical results.

We have investigated the structural, optical and electrocatalytic hydrogen evolution reaction (HER) performance of pristine, Co and Ni substituted WS₂ nanoflakes synthesised by facile hydrothermal method. The XRD pattern confirms the formation of hexagonal WS₂ for both pristine and substituted WS₂ nanoflakes. The FESEM images validate the flake-like structure for both pristine and substituted WS₂. In addition, we have also analysed the Raman and UV-Vis absorbance spectra of the samples. The electrocatalytic studies reveal that the nickel-substituted WS₂ (Ni-WS₂) nanoflakes show superior hydrogen evolution (HER) performance compared to cobalt-substituted WS₂ (Co-WS₂) nanoflakes. Hence, we have varied the Ni concentration and investigated the dependence of Ni content on the electrocatalytic performance. It is found that the electrocatalytic performance of the Ni-WS₂ nanoflakes increases with an increase in Ni content owing to the modified edge structures. Thus, our studies suggest Ni substitution in WS₂ nanostructures can boost electrocatalytic HER performance.

In fringe projection profilometry (FPP), phase shifting profilometry (PSP) combined with temporal phase unwrapping (TPU) algorithms can be used to reliably obtain 3D information from complex measured scenes. However, collecting too many fringe patterns for phase demodulation reduces measurement efficiency. Some studies have shown that deep learning techniques can achieve phase demodulation on single-frame fringe pattern, suggesting that combining deep learning-based phase demodulation with TPU could potentially enable high-speed, high-precision 3D measurements. In this paper, we propose the FPP based on deep learning phase demodulation combined with TPU to achieve 3D measurements using only three fringe patterns. Furthermore, based on different network input strategies and TPU algorithms, the proposed method has four different implementation processes. Comparative experiments analyze the impact of different network input strategies, TPU algorithms, and network structures on the accuracy of phase demodulation and unwrapping. The results demonstrate that using multiple fringe patterns with different frequencies as a joint input significantly improves the phase demodulation accuracy for various frequencies, particularly for lower frequencies, compared to using a single pattern with a neural network. In contrast, enhancing the network structure alone yields relatively modest improvements in phase demodulation accuracy compared to adjusting the input strategy. By analyzing phase demodulation and unwrapping errors, this paper provides guidance on selecting the appropriate implementation process for the proposed method under varying levels of noise interference.

The escalating presence of organic pollutants from industrial activities necessitates urgent measures for their degradation, given their adverse effects on environmental health and ecosystem equilibrium. This study explores the synthesis and characterization of bismuth oxychloride (BiOCl) and zinc oxide (ZnO)-doped BiOCl nanoparticles for enhanced photocatalytic applications. BiOCl, a versatile material with applications in various sectors including cosmetics, pharmaceuticals, and photocatalysis, was synthesized using a novel chemical approach devoid of thermal treatments. ZnO doping induced notable changes in the optical properties of BiOCl, leading to enhanced light absorption within the visible spectrum. Characterization techniques such as X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and UV-visible spectroscopy were employed to analyze the structural and optical properties of the synthesized materials. XRD analysis confirmed the crystalline nature of BiOCl and doped ZnO, while SEM revealed the morphology and microstructure of the nanoparticles. EDX analysis confirmed the elemental composition of the samples, indicating the presence of Bi, O, Cl, and Zn. UV-visible spectroscopy revealed a red shift in the absorption edge upon ZnO doping, with Tauc curves indicating a direct bandgap of 3.26 eV for BiOCl and 3.35 eV for ZnO-doped BiOCl. This research highlights the potential of ZnO-doped BiOCl nanoparticles as efficient photocatalysts for environmental remediation applications.

Co_0.5Ni_0.25Mg_0.25Fe_2−xCr_xO₄ (x = 0.0, 0.05, 0.1, 0.15, 0.2, and 0.25) nano ferrites are studied with different Cr³⁺ concentrations in terms of their synthesis, magnetic properties, and crystal structure. The doped and undoped nanoferrites were prepared using sol-gel auto-combustion. Structural and magnetic research used XRD, FESEM, FTIR, and magnetic data. X-ray diffraction (XRD) patterns of the synthetic samples confirm the presence of a cubic symmetry, crystalline, single-phase spinel structure (Fd-3 m space group). The lattice constant is 8.452 to 8.384 A, and the typical crystallite size is 34 to 24 nm. According to morphology studies conducted with field emission scanning electron microscopy (FESEM), grain size increases with concentration. The FTIR spectra observed vibrational bands identify the tetrahedral and octahedral interstitial complexes in the spinel structure, hence validating the creation of the spinel phase. Additionally, the magnetic hysteresis loop data shows that the saturation magnetization decreases with increasing Cr³⁺ content.

The electrical and magnetic properties of low-dimensional materials like nanorods with defect-free lattice structures are remarkable; yet, structural defects, whether introduced purposefully or inadvertently, significantly modify the magnetic property. Thus, the existence of various cation or anion vacancies and interstitials in SnO₂ may alter their magnetic properties. In this study, Sn_1 − xMn_xO₂ nanoparticles (x = 0.00, 0.02, 0.04, and 0.06) were synthesised using chemical co-precipitation. The XRD pattern shows that manganese (Mn) ions were successfully incorporated into the tetragonal rutile crystal structure of tin oxide (SnO₂). The 445 cm^− 1 band in FTIR spectra indicates Sn–O bond stretching vibrations. The SEM image of SnO₂ shows that Mn inclusion forms nanorods. Sn, Mn, and O in EDX demonstrate the synthesized material’s purity. Photoluminescence peaks about 405 and 421 nm are caused by oxygen vacancies and tin interstitials. An X-ray photoemission spectroscopic analysis indicates a predominance of Sn⁴⁺ with a slight presence of Sn²⁺ valence states, attributed to oxygen vacancies, which leads to the formation of Mn⁴⁺ and Mn²⁺ states in the synthesized material. Mn doped SnO₂ samples’ magnetization versus magnetic field (M–H) curves at ambient temperature showed that increasing Mn concentration from 2 to 6% effectively caused ferromagnetic behaviour owing to Mn ions’ dominant magnetic interaction. To get ferromagnetic characteristics in these materials, the Mn dopant concentration must be properly optimized. The ferromagnetic characteristics of pure and Mn-doped SnO₂ diluted magnetic semiconductors have also been widely studied.