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Unable to Resist
Published in Sharon Ann Holgate, Understanding Solid State Physics, 2021
Diagrams of electron shells (orbits) surrounding a nucleus are a common sight when learning about atomic physics. However, in solid state physics, it is more usual to depict these shells as straight lines. Each electron shell has a different value of energy, as does each corresponding line—which is known as an energy level. Figure 6.12 shows how these two ways of depicting electron energy levels relate to one another.
Semiconductor Devices
Published in Dale R. Patrick, Stephen W. Fardo, Electricity and Electronics Fundamentals, 2020
Dale R. Patrick, Stephen W. Fardo
Energy-level diagrams of insulators, semiconductors, and conductors are shown in Figure 3-4. The valence band is located at the bottom, and the conduction band is at the top. There are other energy levels in the structure of the atom. Each electron shell has a discrete energy level. In electronics we are interested primarily in the valence and conduction bands.
Basic Atomic and Nuclear Physics
Published in Douglas S. McGregor, J. Kenneth Shultis, Radiation Detection, 2020
Douglas S. McGregor, J. Kenneth Shultis
Crucial to the chemistry of atoms is the arrangement of atomic electrons into various electron shells. All electrons with the same n number constitute an electron shell. For n = 1, 2, …, 7, the shells are designated K, L, M, …, Q.
Investigation of f-Element Interactions with Functionalized Diamides of Phenanthroline-Based Ligands
Published in Solvent Extraction and Ion Exchange, 2023
Emma M. Archer, Shane S. Galley, Jessica A. Jackson, Jenifer C. Shafer
Liu et al. examined the Cm-N and Cm-O bond lengths with 5-phenol-Et-Tol-DAPhen and 5-Br-Et-Tol-DAPhen. The bond lengths are surprisingly long compared to the bond lengths of Am3+, Bk3+, and Cf3+ complexes with 5-phenol-Et-Tol-DAPhen and 5-Br-Et-Tol-DAPhen. This was attributed to the electronic structure of Cm3+ having a half full f-electron shell. The effects of substituting the 5-position on the phenanthroline ring with an electron withdrawing group (Br) and an electron donating group (phenol), reveal that the Am-N bond lengths in 1:1 complexes are shortest for 5-phenol-Et-Tol-DAPhen and the longest for 5-Br-Et-Tol- DAPhen.[26,84,90,91] These results preliminarily suggest that electron donating groups substituted in the 5-position on the phenanthroline backbone facilitate shorter bonds.
Elimination of Diethylenetriaminepentaacetic Acid from Effluents from Pharmaceutical Production by Ozonation
Published in Ozone: Science & Engineering, 2022
Fares Daoud, Sebastian Zühlke, Michael Spiteller, Oliver Kayser
However, there are also expedient applications for earth alkali and heavy metals in medical systems. One example is the field of diagnostic imaging. The paramagnetic properties of some elements can be used in magnetic resonance imaging (MRI) to resolve certain areas of the human body in more detail. One of these elements is the lanthanide gadolinium (Gd). The outer electron shell of gadolinium has seven unpaired electrons, which leads to its extreme paramagnetism. However, it is highly toxic in the ionic form, with the LD50 of 0.1 mmol/kg of body weight (Vogl 2013), and therefore harmful when employed for MRI applications. Instead, gadolinium is used in a ligated form that is very stable and unable to permeate the blood–brain barrier. However, some Gd-based contrast agents were reported to cause nephrogenic systemic fibrosis, likely related to dechelation, in several patients. Further, considerably higher resistance to chelate disruption was observed in the so-called macrocyclic forms of gadolinium-based contrast media, as compared to their linear counterparts (Montagne, Toga, and Zlokovic 2016). The complexing agent, DPTA forms such stable ligands with gadolinium, resulting in a nontoxic structure, without compromising its effectiveness in MRI applications.
Radiosensitization with iron nanoparticles under 10–800 Ry photon irradiation: Monte Carlo simulation of particle-to-medium energy transfer
Published in Radiation Effects and Defects in Solids, 2022
Alexander P. Chaynikov, Andrei G. Kochur, Victor A. Yavna
The energy absorbed by an iron atom upon ionization is calculated as the difference between the total energy of an ionized atom after complete cascade relaxation and the atom’s ground state total energy. This is illustrated in Figure 2, where one of the possible ways of the cascade decay of Fe1s-vacancy is presented by an energy diagram for intermediate cascade ions. Figure 2 shows that when a deep electron shell is ionized, most of the energy brought by the incident photon (or electron) is carried away by cascade-produced photons and electrons. In Figure 2, only 2% of absorbed photon energy rests with the Fe atom. This clearly illustrates that a realistic description of energy absorption and transfer mechanisms is impossible without accounting for the cascade decay processes.