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Specific Features of Interatomic Dipole–Dipole Interaction near a Perfectly Conducting Charged Surface
摘要： Specific features of dipole–dipole interaction between two motionless point atoms located near a perfectly conducting charged plate are investigated theoretically within a consistent quantum microscopic approach. These features are analyzed on the basis of the dynamics of cooperative spontaneous decay of excited states of a diatomic quasimolecule. The decay rate is investigated as a function of the interatomic distance, the orientation angle of the quasimolecule with respect to the plane of the plate, and the distance between the quasimolecule and the plate. It is shown that the conducting plate significantly modifies the character of dipole–dipole interaction even when the plate is not charged. When the plate is charged, the Stark splitting of atomic levels leads to an additional modification of the interatomic interaction. The features observed are explained on the basis of the analysis of the spectrum of collective states of diatomic molecules.
关键词： dipole–dipole interaction,quantum microscopic approach,Stark splitting,cooperative spontaneous decay
更新于2025-09-10 09:29:36
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Formation of a Graphene-Like SiN Layer on the Surface Si(111)
摘要： The kinetics of the formation and thermal decomposition of a two-dimensional SiN-(8 × 8) nitride layer on a Si(111) surface is studied. The SiN-(8 × 8) structure is a metastable intermediate phase formed during the nitridation of silicon before the formation of a stable amorphous Si3N4 phase. Studying the SiN-(8 × 8) structure by scanning tunneling microscopy shows its complex structure: it consists of an adsorption (8/3 × 8/3) phase, with the lateral period 10.2 ?, and a honeycomb structure with a ~6 ? side of a hexagon that is turned 30° with respect the adsorption phase. The band gap of the SiN-(8 × 8) phase is measured and found to be ~2.8 eV, which is smaller compared to the band gap of the β-Si3N4 crystal phase 5.3 eV. The interplanar spacings in the (AlN3)/(SiN)2 structure on the Si(111) surface are measured. The spacings are 3.3 and 2.86 ? in SiN and AlN, respectively. Such interplanar spacings are indicative of weak van der Waals interaction between the layers. A model of the SiN-(8 × 8) structure as a flat graphene-like layer is suggested. The model is consistent with the diffraction and microscopy data.
关键词： nitride layer,van der Waals interaction,Si(111) surface,SiN-(8 × 8),graphene-like
更新于2025-09-10 09:29:36
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Probing the Electronic Properties of Monolayer MoS <sub/>2</sub> via Interaction with Molecular Hydrogen
摘要： This work presents a detailed experimental investigation of the interaction between molecular hydrogen (H2) and monolayer MoS2 field effect transistors (MoS2 FET), aiming for sensing application. The MoS2 FET exhibits a response to H2 that covers a broad range of concentration (0.1–90%) at a relatively low operating temperature range (300–473 K). Most important, H2 sensors based on MoS2 FETs show desirable properties such as full reversibility and absence of catalytic metal dopants (Pt or Pd). The experimental results indicate that the conductivity of MoS2 monotonically increases as a function of the H2 concentration due to a reversible charge transferring process. It is proposed that such process involves dissociative H2 adsorption driven by interaction with sulfur vacancies in the MoS2 surface (VS). This description is in agreement with related density functional theory studies about H2 adsorption on MoS2. Finally, measurements on partially defect-passivated MoS2 FETs using atomic layer deposited aluminum oxide consist of an experimental indication that the VS plays an important role in the H2 interaction with the MoS2. These findings provide insights for future applications in catalytic process between monolayer MoS2 and H2 and also introduce MoS2 FETs as promising H2 sensors.
关键词： hydrogen gas sensor,gas interaction,hydrogen detection,monolayer MoS2,field effect transistors
更新于2025-09-10 09:29:36
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Self-Generation of Chaotic Microwave Signal in Spin Wave Optoelectronic Generator
摘要： The self-generation of a chaotic microwave signal in a spin-wave optoelectronic generator has been experimentally investigated for the first time. The generator was a ring circuit, in the microwave path of which there was a spin-wave delay line on the film of an yttrium iron garnet (YIG) and a microwave amplifier. The optical path contained a fiber optic delay line. The nonlinear element of the generator was a film of YIG, which worked under the conditions of four-wave parametric interaction of spin waves. It has been shown that it is possible to generate monochromatic, periodic, quasi-periodic, and chaotic microwave signals by controlling the gain coefficient of the ring. The parameters characterizing the chaotic signal that are generated by the ring have been determined.
关键词： spin-wave optoelectronic generator,chaotic microwave signal,YIG film,four-wave parametric interaction
更新于2025-09-10 09:29:36
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Ultrafast mixing of radial and spin states driven by transient magnetic field in concentric double quantum ring in presence of Dresselhaus spin-orbit interaction
摘要： We consider the single- and two-electron systems confined in concentric double quantum ring (DQR) nanostructure which interacts with transient perpendicular magnetic field oscillating with THz frequency. For this purpose we find the solutions of time-dependent Schr?dinger equation utilizing Configuration Interaction method. We found that the transient magnetic field mixes the radial states, what trigger off the charge density oscillations in this direction, and these may be accompanied by spin oscillations, provided that a spin-orbit interaction (SOI) is involved. The pattern of density oscillations is more regular than those obtained for single- and two-electron spins what results from less complicated excitation energy spectra if SOI is not present in the system. The latter can be made more regular, i.e. the fluctuations of frequency and amplitude of spin oscillations shall be smaller, provided that the sign of the magnetic field at the begining of time evolution is chosen apropriately since not all energy levels corresponding to bJz = bLz (cid:0) bSz eigenstates have mirror symmetry in relation to B ! (cid:0)B transformation. Our outcomes indicate, that the combined effect of a few-picosecond-long magnetic pulse and SOI on electron spin in DQR would enable one to perform transition between spin-up and spin-down states within 2 ps.
关键词： spin-orbit interaction,quantum ring,magnetic pulse
更新于2025-09-10 09:29:36
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Unsupervised Nonlinear Spectral Unmixing of Satellite Images Using the Modified Bilinear Model
摘要： Episodes of mixing pixels in satellite imageries are more prevalent. Hence, spectral unmixing approach is used to perform the sub-pixel classification of satellite images. Many unmixing works were done based on the assumption that the pixels are linearly mixed (single interaction) but in real scenarios, the pixels are nonlinearly mixed due to interactions. Fan model and generalized bilinear model consider only the bilinear interactions for nonlinear unmixing. In reality, multiple interactions between the various classes are also present in the image. In this work, a new model, ‘modified bilinear model’ is proposed to perform the nonlinear unmixing process that considers the entire single, bilinear and multiple interactions into account. This system adaptively changes the mixing model on per pixel basis depending on the nonlinearity parameter. It has been tested with the multispectral, synthetic and real hyperspectral datasets and also illustrated notable advantages compared with the other methods.
关键词： Multiple interaction,Spectral unmixing,Endmember extraction,Nonlinear unmixing
更新于2025-09-10 09:29:36
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High power THz-range Wave generation based on Transformation of Plasma Waves Pumped by High-current Relativistic Electron Beam
摘要： The beam-plasma interaction system allows one to generate high-power sub-mm waves (frequency interval 0.1÷1 THz) by usage of mechanism of plasma wave transformation [1]. This way gives possibility to achieve multi megawatt power with the promptly varying frequency that can be necessary for various practical applications. The original project of a sub-mm wave based on transformation of plasma waves pumped by a kA-current relativistic electron beam is developed at the GOL-PET facility. We present novel results on the study of mechanisms of sub-mm wave emission by the processes of plasma wave transformation in electromagnetic one in case of the strong beam-plasma interaction.
关键词： sub-mm wave generation,plasma waves,beam-plasma interaction,relativistic electron beam,THz-range
更新于2025-09-10 09:29:36
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Neuroergonomics || Why is Eye Tracking an Essential Part of Neuroergonomics?
摘要： Neuroergonomics generally promotes the use of brain imaging techniques or electroencephalography to measure the neural mechanisms underpinning human performance in complex real-life situations, so eye tracking is not the first type of neuroergonomics method that comes to mind. Why bring eye movements and pupillary changes into neuroergonomics? Human vision is tightly coupled to a majority of our activities, and vision provides the brain with a wealth of information. It is difficult, though not impossible, to imagine, for example, an aircraft pilot with visual impairment. The eyes are an important mediator between the environment and the brain, facilitating interaction with our everyday world. Our eyes constantly move to direct our foveas (the small region of the central retina that has highest visual acuity) to objects of interest. Light passes through the pupil to the retina, which then nervates to the brain. Importantly, the retina is a part of the embryonic diencephalon that progressively evolves into a complex connection using several neural pathways to support visual perception and attentional orientation. Hence eye tracking, though an indirect measure of brain activity, is in a way the technique that measures with the closest proximity to the brain–the retina is in fact the only part of the brain visible (e.g., to an optometrist) by the naked eye.
关键词： Pupillometry,Eye Movements,Neuroergonomics,Eye Tracking,Human-Machine Interaction
更新于2025-09-10 09:29:36
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Three-dimensional modulations on the states of polarization of light fields
摘要： Light ?elds with spatially structured states of polarization (SoPs) are gathering increasing attention because of their potential applications from optical imaging and micromanipulation to classical and quantum communications. Meanwhile, the concepts within structured light ?elds have been extended and applied to acoustic, electron, and matter waves. In this article, we review recent developments of the SoP modulation of light ?elds, especially focusing on three-dimensional (3D) modulations on the SoPs of light ?elds. The recent progress and novel implementations based on 3D spin-dependent separation are discussed. Following the discussions to this physical phenomenon, we then describe recent developments on the vector ?elds with 3D structured SoP and intensity distributions, namely, 3D vector ?elds. The discussed phenomena inspire us to explore other structured light ?elds for the expansion of applications in biomedical, information science, quantum optics, and so on.
关键词： vector ?eld,phase,polarization,spin–orbit interaction
更新于2025-09-10 09:29:36
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Color-tunable particles through affinity interactions between water-insoluble protein and soluble dyes
摘要： This research is focused on the delivery of color using zein particles as a carrier and contributes to understanding the interactions between colorants and zein. Co-precipitation of purified zein protein with anionic dyes such as sulfonate group containing azo-dyes (patent blue sodium salt, azorubine, and fast green FCF) are used to prepare red, green, and blue colored nanoparticles. These dyes had electrostatic interactions with zein and they remained bound in the zein particles even after dialysis. This was not the case for purpurin, for with hydrogen bonding was expected as interaction. Upon increasing dye concentration, the particle sizes increased as a result of a change in the kinetics of precipitation, which was affected by the association between zein and the dye. However, the encapsulation efficiency continued to be very high and no plateau was reached for the used concentrations. The post-addition of dye on undyed zein particles was used to confirm that there is indeed a high affinity between the dye and the protein. The amount of free dye was determined and the affinity was again found to be high (dye adsorption ?95%). The amount of dye incorporated into the particles and the resulting color were similar using both techniques. These results show that there is a high affinity between the zein protein and the dye, and may be exploited to produce bio-based and optically-functionalized nanoparticles using zein as a carrier.
关键词： Zein,dye,color determination,interaction,co-precipitation
更新于2025-09-10 09:29:36