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Experimental and Characterization Techniques
Published in Amit Sachdeva, Pramod Kumar Singh, Hee Woo Rhee, Composite Materials, 2021
Rahul, Rakesh K. Sonker, P. K. Shukla, Pramod K. Singh, Zishan H. Khan
TEM has been used to study the size, shape, and distribution of nanoscale materials [46]. The schematic diagram of a typical TEM is represented in Figure 5.20 [47]. A thin, solid specimen (< 200 nm) is bombarded in vacuum with a highly focused, monoenergetic beam of electrons. The smaller de Broglie wavelength associated with the high-energy electron beam is responsible for the high resolution and the ability to focus the electron beam. As an example, electrons with an energy of 100 keV correspond to a de Broglie wavelength of 3.7 × 10−3 nm. In general, TEM is expected to use electron beams having energy in the range of 20 to 200 keV. In this energy range, the beam has enough energy to propagate through the specimen. A series of electromagnetic lenses are used to magnify the transmitted electron signals [48].
Low-Power Optoelectronic Interconnects on Two-Dimensional Semiconductors
Published in Krzysztof Iniewski, Santosh K. Kurinec, Sumeet Walia, Energy Efficient Computing & Electronics, 2019
Electron energy loss spectroscopy (EELS), on the other hand, offers high-resolution, direct, unambiguous measures of optoelectronic interactions between nanoparticles and two-dimensional semiconductors that avoid the confounding effects intrinsic to optical measures. EELS is performed in a scanning transmission electron microscope. Nanometer-scale resolution is provided by the de Broglie wavelength of the electron source. Electron optics of the EELS monochromation system are used to distinguish the amount of electron energy lost at a particular frequency. This energy loss corresponds to the probability that an electromagnetic event such as a plasmon or exciton occurs. Irradiation by a fast-moving electron beam is the electromagnetic equivalent of interrogation by a broadband electromagnetic source. It may result in induction of bright, dark, and or hybrid plasmon modes on metal nanoantennas. The appearance, energy, and bandwidth of these modes varies as a result of the impact point of the sub-nanometer electron probe121,122 as well as the composition, geometry and environment of the nanoparticle and/or two-dimensional semiconductor.123–131 EELS was used as early as 2014 to measure direct electron transfer from gold ellipses to graphene at up to 20% quantum efficiency.130
Physics of Important Developments That Predestined Graphene
Published in Andre U. Sokolnikov, Graphene for Defense and Security, 2017
In real heterostructures ρ is fixed by doping and the value of the gate voltage is not precisely quantized. The above-mentioned imperfection in the quantum Hall experiment manifests itself in the Hall plateau formation. The Hall conductance in the plateau is equal to a multiplication of e2/h (the parallel resistance is zero in a plateau). The explanation is that the new state adiabatically transformed into a filled Landau with the exception of excitation with partial charges8. It is argued that a perfect system is invariant along the x-direction and σxy=Pc/B; ρ is not quantized charge density. The high probability of the electron cloud in the z-direction makes the electron fully-quantized in a f(z) bound state in a potential well narrower than the de Broglie wavelength for the electron, λ=hp. The de Broglie wavelength is the wavelength, λ, associated with a particle and connected with its momentum, p.
Neutron diffraction investigation of strontium tellurite glass, anti-glass and crystalline phases
Published in Phase Transitions, 2020
Rajinder Kaur, Atul Khanna, Margit Fábián
Neutron diffraction (ND) studies of the strontium tellurite glass, anti-glass and crystalline samples were carried out at the 2-axis PSD diffractometer at Budapest Neutron Centre, Hungary [30]. The diffraction pattern was measured in the momentum transfer, Q range of 0.45-9.8 Å−1 using monochromatic neutrons of de Broglie wavelength, λ = 1.068 Å. The powder specimens of about 3–4 g were filled in thin-walled cylindrical vanadium can of diameter 8 mm. The data were corrected for the background, absorption and multiple scattering and normalized with vanadium standard to obtain the structure factor, S(Q). The neutron diffraction weight factors, of the atomic pairs in the glass network are given in Table 2 and calculated as below: where ci, cj are the molar fractions of the components, bi, bj are the coherent neutron scattering lengths, S(Q) is the total structure factor and is the partial structure factor.
Electron impact scattering study on chlorobenzene
Published in Molecular Physics, 2019
Dineshkumar Prajapati, Hitesh Yadav, Minaxi Vinodkumar, Chetan Limbachiya, P. C. Vinodkumar
In Figure 12, the present TCS result is in better agreement with experimental results of Makochekanwa et al. [17] and it overestimates the data given by Lunt et al. [16] It is also in better agreement with the theoretical results obtained in the IAM-SCAR method by Barbosa et al. [3] while it overestimates the data obtained using the SMCPP-SEP model by Barbosa et al. [3] The reason for this difference is the improper inclusion of the polarisation effect in the SMCPP-SEP model. The difference observed with the data of Singh et al. [20] can be attributed to the difference between the single centre expansion employed in our calculations as against the multi-centre expansion employed by them. Incident energy and De-Broglie wavelength are inversely proportional. This relation clearly suggests that at high energies the de-Broglie wavelength is small and at low energy, it is high in magnitude. Therefore, the single centre expansion being compact gives better results. Here the incident electron sees the whole target as one entity. While at high energy corresponds to lower de-Broglie wavelength, the incident electron sees the whole target as separate entities and hence multi-centre expansion is more viable and it will give better result than that of single-centre expansion. Thus, multi-centre approach adopted by Singh et al. [20] are in good agreement with other reported data at high energy. While the present result is in better agreement in the intermediate energy range with all other reported data.
Nucleus-nucleus scattering and the Rutherford experiment
Published in Journal of the Royal Society of New Zealand, 2021
First the attractive nuclear potential was described in terms of a more realistic form factor that described better the shape of the nucleus (Figure 7) (Woods and Saxon 1954). This form assumes that the potential decreases over some distance, the potential diffuseness, at the nuclear surface. It is also important to consider that the projectile and the atomic nucleus act somewhat as a matter wave. The de Broglie wavelength is not negligible as compared to the dimension of the scattering particles. So, people have begun to describe the particle scattering in terms of its wave nature and they develop what is called the optical model (Feshbach et al. 1954).