Quantum transmission through the n-p-n heterojunction of massive 8-Pmmn borophene

2021 ◽  
Author(s):  
Guo-Na Yu ◽  
Guang-Yu Yi ◽  
Wei-Bin Cui ◽  
Lian-Lian Zhang ◽  
Xue-Si Li ◽  
...  
Keyword(s):  
Energy Range ◽  
Specular Reflection ◽  
Effective Energy ◽  
Transmission Property ◽  
Dirac Mass ◽  
Equal Energy ◽  
Quantum Transmission ◽  
Energy Surfaces

Abstract We investigate the quantum transmission through the n-p-n heterojunction of massive 8-Pmmn borophene. It is found that the Dirac mass of the electron interacts with the anisotropy of the 8-Pmmn borophene, leading to the occurrence of new transmission behaviors in this n-p-n heterojunction. Firstly, the effective energy range of nonzero transmission can be reduced but deviates from the mass amplitude, which induces the further controllability of the transmission property. Secondly, even if the equal-energy surfaces in the p and n parts do not encounter in the k-space, finite transmission is allowed to occur as well. In addition, the existence of Dirac mass can change the reflection manner from the retroreflection to the specular reflection under appropriate conditions.

A focusing X-ray telescope for use in the study of extraterrestrial X-ray sources in the energy range 20–140 keV

1968 ◽  
Vol 46 (10) ◽  
pp. S1103-S1106 ◽  
Author(s):  
T. R. Llndquist ◽  
W. R. Webber
Keyword(s):  
Energy Range ◽  
Rock Salt ◽  
Angular Resolution ◽  
X Rays ◽  
Effective Energy ◽  
Optimum Thickness ◽  
Bragg Condition ◽  
X Ray ◽  
Area Efficiency ◽  
Salt Crystals

We have designed and tested a focusing X-ray telescope with an angular resolution (FWHM) of 1.0° for the study of extraterrestrial X-ray sources in the energy range 20–140 keV. The telescope's lens is an array of rock salt crystals (each of which is approximately one inch square), mounted on a 6-ft-diameter paraboloidal frame. The lens is located 9.5 ft above a 2-in.-diameter NaI crystal and PM tube (which measures the energy of the incident X ray). X rays passing through the salt crystals undergo a 2θ deflection if the Bragg condition for reflection, nλ = 2d sin θ, is approximately satisfied. Optimum thickness and effective energy bandwidths for such reflections have been determined for energies in the telescope's operating range. The area-efficiency product of the lens is approximately 8 times the NaI crystal area from 20 to 40 keV, giving a real improvement in the signal-to-background ratio. Crystals more nearly perfect than rock salt offer the possibility of increased gain over narrow energy intervals. Polarization measurements of the incident X rays may also be made.

scholarly journals Potential Energy Landscape of CO Adsorbates on NaCl(100) and Implications in Isomerization of Vibrationally Excited CO

2020 ◽  
Author(s):  
Jun Chen ◽  
Seenivasan Hariharan ◽  
Joerg Meyer ◽  
Hua Guo
Keyword(s):  
Potential Energy ◽  
Energy Range ◽  
First Principles ◽  
Potential Energy Surfaces ◽  
Energy Landscape ◽  
First Principles Calculations ◽  
Small Energy ◽  
Vibrationally Excited ◽  
Potential Energy Landscape ◽  
Energy Surfaces

Several full-dimensional potential energy surfaces (PESs) are reported for vibrating CO adsorbates at two coverages on a rigid NaCl(100) surface based on first principles calculations. These PESs reveal a rather flat energy landscape for physisorption of vibrationless CO on NaCl(100), evidenced by various C-down adsorption patterns within a small energy range. Agreement with available experimental results is satisfactory, although quantitative differences exist. These PESs are used to explore isomerization pathways between the C-down and higher energy O-down configurations, which reveal a significant isomerization barrier. As CO vibration is excited, however, the energy order of the two isomer changes, which helps to explain the experimental observed flipping of vibrationally excited CO adsorbates.

scholarly journals Attachment of Electrons to Molecules at meV Resolution

1992 ◽  
Vol 45 (3) ◽  
pp. 263 ◽  
Author(s):  
D Klar ◽  
M-W Ruf ◽  
H Hotop
Keyword(s):  
Energy Range ◽  
Energy Resolution ◽  
Electron Attachment ◽  
Effective Energy ◽  
Near Threshold

A selective discussion of electron attachment to molecules is presented with emphasis on recent studies of SF6, carried out with a novel laser photoelectron attachment (LPA) method in the energy range 0�1-170 me V with an effective energy resolution around 0�1 me V near threshold.

scholarly journals Potential Energy Landscape of CO Adsorbates on NaCl(100) and Implications in Isomerization of Vibrationally Excited CO

2020 ◽  
Author(s):  
Jun Chen ◽  
Seenivasan Hariharan ◽  
Joerg Meyer ◽  
Hua Guo
Keyword(s):  
Potential Energy ◽  
Energy Range ◽  
First Principles ◽  
Potential Energy Surfaces ◽  
Energy Landscape ◽  
First Principles Calculations ◽  
Small Energy ◽  
Vibrationally Excited ◽  
Potential Energy Landscape ◽  
Energy Surfaces

Several full-dimensional potential energy surfaces (PESs) are reported for vibrating CO adsorbates at two coverages on a rigid NaCl(100) surface based on first principles calculations. These PESs reveal a rather flat energy landscape for physisorption of vibrationless CO on NaCl(100), evidenced by various C-down adsorption patterns within a small energy range. Agreement with available experimental results is satisfactory, although quantitative differences exist. These PESs are used to explore isomerization pathways between the C-down and higher energy O-down configurations, which reveal a significant isomerization barrier. As CO vibration is excited, however, the energy order of the two isomer changes, which helps to explain the experimental observed flipping of vibrationally excited CO adsorbates.

Solar Flare Energetic Neutral Emission Measurements in the Project Coronas-I

1994 ◽  
Vol 144 ◽  
pp. 635-639
Author(s):  
J. Baláž ◽  
A. V. Dmitriev ◽  
M. A. Kovalevskaya ◽  
K. Kudela ◽  
S. N. Kuznetsov ◽  
...  
Keyword(s):  
Solar Flare ◽  
Energy Range ◽  
Gamma Rays ◽  
Pulse Shape ◽  
Gamma Ray ◽  
Pulse Shape Discrimination ◽  
Shape Discrimination ◽  
Solar Neutron ◽  
Low Altitude

AbstractThe experiment SONG (SOlar Neutron and Gamma rays) for the low altitude satellite CORONAS-I is described. The instrument is capable to provide gamma-ray line and continuum detection in the energy range 0.1 – 100 MeV as well as detection of neutrons with energies above 30 MeV. As a by-product, the electrons in the range 11 – 108 MeV will be measured too. The pulse shape discrimination technique (PSD) is used.

Use of fractals to describe microstructures of porous thick-film platinum electrodes

1992 ◽  
Vol 50 (1) ◽  
pp. 314-315
Author(s):  
Steven D. Toteda
Keyword(s):  
Fractal Dimension ◽  
Power Plants ◽  
Electrical Response ◽  
Cubic Phase ◽  
Platinum Electrodes ◽  
Fine Grained ◽  
Impedance Response ◽  
Platinum Particles ◽  
Energy Surfaces ◽  
Highly Porous

Zirconia oxygen sensors, in such applications as power plants and automobiles, generally utilize platinum electrodes for the catalytic reaction of dissociating O2 at the surface. The microstructure of the platinum electrode defines the resulting electrical response. The electrode must be porous enough to allow the oxygen to reach the zirconia surface while still remaining electrically continuous. At low sintering temperatures, the platinum is highly porous and fine grained. The platinum particles sinter together as the firing temperatures are increased. As the sintering temperatures are raised even further, the surface of the platinum begins to facet with lower energy surfaces. These microstructural changes can be seen in Figures 1 and 2, but the goal of the work is to characterize the microstructure by its fractal dimension and then relate the fractal dimension to the electrical response. The sensors were fabricated from zirconia powder stabilized in the cubic phase with 8 mol% percent yttria. Each substrate was sintered for 14 hours at 1200°C. The resulting zirconia pellets, 13mm in diameter and 2mm in thickness, were roughly 97 to 98 percent of theoretical density. The Engelhard #6082 platinum paste was applied to the zirconia disks after they were mechanically polished ( diamond). The electrodes were then sintered at temperatures ranging from 600°C to 1000°C. Each sensor was tested to determine the impedance response from 1Hz to 5,000Hz. These frequencies correspond to the electrode at the test temperature of 600°C.

Forensic applications of IR infrared microscopic internal reflection spectroscopy

1992 ◽  
Vol 50 (2) ◽  
pp. 1528-1529
Author(s):  
Edward G. Bartick ◽  
John A. Reffner
Keyword(s):  
Specular Reflection ◽  
Forensic Analysis ◽  
Attenuated Total Reflection ◽  
Internal Reflection ◽  
Standard Size ◽  
Ir Microscopy ◽  
Ir Analysis ◽  
Plastic Explosives ◽  
Internal Reflection Spectroscopy ◽  
Reflectance Measurements

Since the introduction of commercial Fourier transform infrared (FTIR) microscopic systems in 1983, IR microscopy has developed as an important analytical tool in research, industry and forensic analysis. Because of the frequent encounter of small quantities of physical evidence found at crime scenes, spectroscopic IR microscopes have proven particularly valuable for forensic applications. Transmittance and reflectance measurements have proven very useful. Reflection-absorption, specular reflection, and diffuse reflection have all been applied. However, it has been only very recently that an internal reflection (IRS) objective has been commercially introduced.The IRS method, also known as attenuated total reflection (ATR), has proven very useful for IR analysis of standard size samples. The method has been applied to adhesive tapes, plastic explosives, and general applications in the analysis of opaque materials found as evidence. The small quantities or uncontaminated areas of specimens frequently found requiring forensic analysis will often be directly applicable to microscopic IRS analysis.

Valence electron energy loss spectroscopy in reflection geometry

1989 ◽  
Vol 47 ◽  
pp. 378-379
Author(s):  
J. Liu ◽  
J. M. Cowley
Keyword(s):  
Energy Loss ◽  
Valence Electron ◽  
Interband Transition ◽  
Specular Reflection ◽  
Three Dimensional ◽  
Electron Excitation ◽  
Transmission Electron ◽  
Yield Information ◽  
Valence Bands ◽  
Excitation Processes

The low energy loss region of a EELS spectrum carries information about the valence electron excitation processes (e.g., collective excitations for free electron like materials and interband transitions for insulators). The relative intensities and the positions of the interband transition energy loss peaks observed in EELS spectra are determined by the joint density of states (DOS) of the initial and final states of the excitation processes. Thus it is expected that EELS in reflection mode could yield information about the perturbation of the DOS of the conduction and valence bands of the bulk crystals caused by the termination of the three dimensional periodicity at the crystal surfaces. The experiments were performed in a Philipps 400T transmission electron microscope operated at 120 kV. The reflection EELS spectra were obtained by a Gatan 607 EELS spectrometer together with a Tracor data acquisition system and the resolution of the spectrometer was about 0.8 eV. All the reflection spectra are obtained from the specular reflection spots satisfying surface resonance conditions.

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