The Effects of Nonzero Total Electron Spin in theX̃3B1State of Methylene CH2

1997 ◽  
Vol 183 (2) ◽  
pp. 398-406 ◽  
Author(s):  
Igor N. Kozin ◽  
Per Jensen
Keyword(s):  
Electron Spin ◽  
Total Electron

Pulse Shaped Dynamic Nuclear Polarization Under Magic Angle Spinning

2019 ◽  
Author(s):  
ASIF EQUBAL ◽  
Kan Tagami ◽  
Songi Han
Keyword(s):  
Electron Spin ◽  
Lattice Relaxation ◽  
Magic Angle Spinning ◽  
Spin Lattice Relaxation ◽  
Magic Angle ◽  
Total Electron ◽  
Spin Lattice ◽  
Maximum Benefit ◽  
Selective Saturation ◽  
Angle Spinning

In this paper, we report on an entirely novel way of improving the MAS-DNP efficiency by shaped μw pulse train irradiation for fast and broad-banded (FAB) saturation of the electron spin resonance. FAB-DNP achieved with Arbitrary Wave Generated shaped μw pulse trains facilitates effective and selective saturation of a defined fraction of the total electron spins, and provides superior control over the DNP efficiency under MAS. Experimental and quantum-mechanics based numerically simulated results together demonstrate that FAB-DNP significantly outperforms CW-DNP when the EPR-line of PAs is broadened by conformational distribution and exchange coupling. We demonstrate that the maximum benefit of FAB DNP is achieved when the electron spin-lattice relaxation is fast relative to the MAS frequency, i.e. at higher temperatures and/or when employing metals as PAs. Calculations predict that under short T<sub>1e </sub>conditions AWG-DNP can achieve as much as ~4-fold greater enhancement compared to CW-DNP.

Electron Band Structure of MnGaN

2007 ◽  
Vol 1040 ◽  
Author(s):  
Dimiter Alexandrov ◽  
Nikolaus Dietz ◽  
Ian Ferguson ◽  
Hang Yu
Keyword(s):  
Band Structure ◽  
Electron Spin ◽  
Energy Levels ◽  
Band Diagram ◽  
Total Electron ◽  
Electron Band ◽  
Hybrid Orbital ◽  
Semiconductor Alloy ◽  
Ternary Semiconductor ◽  
Electron Band Structure

AbstractInvestigation of the properties of MnxGa1-xN semiconductor alloy is performed on the basis of LCAO electron band structure of this semiconductor. The authors model this alloy on the basis of Mn substitutions on Ga sites and it is identified that the ternary semiconductor MnxGa1-xN has two tetrahedral binary constituents – GaN and MnN. It is found that the sp3 hybrid orbital of the N atom attracts an electron from the 3d orbital of the Mn atom and thus the Mn-N bonding becomes of sp3 type. In this way the total electron spin of the 3d orbital of the Mn atom becomes 3/2, which determines that the energy levels 4F, 4D, 4P and 4G belonging to this orbital to be occupied. LCAO electron band structure of wurtzite MnxGa1-xN for points Γυc1 and Γυv15 (υ = 1, 2, 3, 4, 5) is calculated by previously developed method and the positions of the levels 4F, 4D, 4P and 4G in this structure are determined. It is found dependence of the total electron spin of the Mn atom on the position of the Fermi level in the electron band diagram of MnxGa1-xN. Also it is found that the total spin depends on electron inter-band transitions as well. The optical properties of the wurtzite MnxGa1-xN are determined as well.

Electron Spin–Spin Contact Interaction and Mass-Variation and Darwin Relativistic Corrections in Isoelectronic Series

1972 ◽  
Vol 50 (1) ◽  
pp. 42-46
Author(s):  
B. W. N. Lo ◽  
K. M. S. Saxena ◽  
S. Fraga
Keyword(s):  
Contact Interaction ◽  
Electron Spin ◽  
Mass Variation ◽  
Total Electron ◽  
Relativistic Corrections ◽  
Isoelectronic Series

The values of the total electron spin–spin contact interaction and the mass-variation and Darwin relativistic corrections have been calculated for a number of isoelectronic series. It is observed that the main contributions to these corrections, that are not negligible, are made by the inner electrons.

Complete Electron Spin–Spin Contact Interaction in Atoms with fn Configurations

1972 ◽  
Vol 50 (9) ◽  
pp. 870-872 ◽  
Author(s):  
K. M. S. Saxena ◽  
B. W. N. Lo ◽  
S. Fraga
Keyword(s):  
Contact Interaction ◽  
Electron Spin ◽  
Ground States ◽  
Neutral Atoms ◽  
Total Electron ◽  
Hartree Fock ◽  
Positive Ions

The total electron spin–spin contact interaction, including both the inter and intrashell contributions, has been evaluated from existing numerical Hartree–Fock functions, for the ground states of the neutral atoms and doubly and triply charged positive ions from La to Yb.

Pulse Shaped Dynamic Nuclear Polarization Under Magic Angle Spinning

2019 ◽  
Author(s):  
ASIF EQUBAL ◽  
Kan Tagami ◽  
Songi Han
Keyword(s):  
Electron Spin ◽  
Lattice Relaxation ◽  
Magic Angle Spinning ◽  
Spin Lattice Relaxation ◽  
Magic Angle ◽  
Total Electron ◽  
Spin Lattice ◽  
Maximum Benefit ◽  
Selective Saturation ◽  
Angle Spinning

In this paper, we report on an entirely novel way of improving the MAS-DNP efficiency by shaped μw pulse train irradiation for fast and broad-banded (FAB) saturation of the electron spin resonance. FAB-DNP achieved with Arbitrary Wave Generated shaped μw pulse trains facilitates effective and selective saturation of a defined fraction of the total electron spins, and provides superior control over the DNP efficiency under MAS. Experimental and quantum-mechanics based numerically simulated results together demonstrate that FAB-DNP significantly outperforms CW-DNP when the EPR-line of PAs is broadened by conformational distribution and exchange coupling. We demonstrate that the maximum benefit of FAB DNP is achieved when the electron spin-lattice relaxation is fast relative to the MAS frequency, i.e. at higher temperatures and/or when employing metals as PAs. Calculations predict that under short T<sub>1e </sub>conditions AWG-DNP can achieve as much as ~4-fold greater enhancement compared to CW-DNP.

The Three-dimensional structure of frozen-hydrated nudaurelia capensis β virus

1987 ◽  
Vol 45 ◽  
pp. 650-651
Author(s):  
N. H. Olson ◽  
T. S. Baker ◽  
Wu Bo Mu ◽  
J. E. Johnson ◽  
D. A. Hendry
Keyword(s):  
South African ◽  
Rna Virus ◽  
Carbon Film ◽  
Three Dimensional ◽  
Dimensional Structure ◽  
Electron Dose ◽  
Total Electron ◽  
Three Dimensional Structure ◽  
Negative Stain ◽  
Dimensional Reconstruction

Nudaurelia capensis β virus (NβV) is an RNA virus of the South African Pine Emperor moth, Nudaurelia cytherea capensis (Lepidoptera: Saturniidae). The NβV capsid is a T = 4 icosahedron that contains 60T = 240 subunits of the coat protein (Mr = 61,000). A three-dimensional reconstruction of the NβV capsid was previously computed from visions embedded in negative stain suspended over holes in a carbon film. We have re-examined the three-dimensional structure of NβV, using cryo-microscopy to examine the native, unstained structure of the virion and to provide a initial phasing model for high-resolution x-ray crystallographic studiesNβV was purified and prepared for cryo-microscopy as described. Micrographs were recorded ∼1 - 2 μm underfocus at a magnification of 49,000X with a total electron dose of about 1800 e-/nm2.

The measurement of inner-shell ionization cross aections by electron impact in a TEM

1992 ◽  
Vol 50 (2) ◽  
pp. 1266-1267
Author(s):  
Raynald Gauvin ◽  
Gilles L'Espérance
Keyword(s):  
Electron Impact ◽  
Cross Sections ◽  
Weight Fraction ◽  
Thin Foil ◽  
Specimen Thickness ◽  
Ionization Cross ◽  
Electron Dose ◽  
Total Electron ◽  
Inner Shell Ionization ◽  
Shell Ionization

Values of cross sections for ionization of inner-shell electrons by electron impact are required for electron probe microanalysis, Auger-electron spectroscopy and electron energy-loss spectroscopy. In this work, the results of the measurement of inner-shell ionization cross-sections by electron impact, Q, in a TEM are presented for the K shell.The measurement of QNi has been performed at 120 KeV in a TEM by measuring the net X-ray intensity of the Kα line of Ni, INi, which is related to QNi by the relation :(1)where i is the total electron dose, (Ω/4π)is the fractional solid angle, ω is the fluorescence yield, α is the relative intensity factor, ε is the Si (Li) detector efficiency, A is the atomic weight, ρ is the sample density, No is Avogadro's number, t' is the distance traveled by the electrons in the specimen which is equal to τ sec θ neglecting beam broadening where τ is the specimen thickness and θ is the angle between the electron beam and the normal of the thin foil and CNi is the weight fraction of Ni.

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