Pole Dominance and Low-Energy Theorem in the Radiative Decays of Charged Kaons

1969 ◽  
Vol 177 (5) ◽  
pp. 2573-2578 ◽  
Author(s):  
Ronald Rockmore
Keyword(s):  
Low Energy ◽  
Radiative Decays ◽  
Pole Dominance

scholarly journals Photophysical Properties of Spirobifluorene-Based o-Carboranyl Compounds Altered by Structurally Rotating the Carborane Cages

Molecules ◽  
2019 ◽  
Vol 24 (22) ◽  
pp. 4135
Author(s):  
Seonah Kim ◽  
Hyunhee So ◽  
Ji Hye Lee ◽  
Hyonseok Hwang ◽  
Hyoshik Kwon ◽  
...  
Keyword(s):  
Radiative Decay ◽  
Photophysical Properties ◽  
High Energy ◽  
Low Energy ◽  
Radiative Decays ◽  
Absorption Bands ◽  
Molecular Features ◽  
Td Dft ◽  
Structural Fluctuations ◽  
Energy Emissions

9,9′-Spirobifluorene-based o-carboranyl compounds C1 and C2 were prepared and fully characterized by multinuclear nuclear magnetic resonance (NMR) spectroscopy and elemental analysis. The solid-state structure of C1 was also determined by single-crystal X-ray diffractometry. The two carboranyl compounds display major absorption bands that are assigned to π−π* transitions involving their spirobifluorene groups, as well as weak intramolecular charge-transfer (ICT) transitions between the o-carboranes and their spirobifluorene groups. While C1 only exhibited high-energy emissions (λem = ca. 350 nm) in THF at 298 K due to locally excited (LE) states assignable to π−π* transitions involving the spirobifluorene group alone, a remarkable emission in the low-energy region was observed in the rigid state, such as in THF at 77 K or the film state. Furthermore, C2 displays intense dual emissive patterns in both high- and low-energy regions in all states. Electronic transitions that were calculated by time-dependent-DFT (TD-DFT) for each compound based on ground (S0) and first-excited (S1) state optimized structures clearly verify that the low-energy emissions are due to ICT-based radiative decays. Calculated energy barriers that are based on the relative energies associated with changes in the dihedral angle around the o-carborane cages in C1 and C2 clearly reveal that the o-carborane cage in C1 rotates more freely than that in C2. All of the molecular features indicate that ICT-based radiative decay is only available to the rigid state in the absence of structural fluctuations, in particular the free-rotation of the o-carborane cage.

Low-energy theorem for radiative decays of hyperons

1968 ◽  
Vol 57 (1) ◽  
pp. 146-153
Author(s):  
J. Leal Ferreira ◽  
J. Soffer
Keyword(s):  
Low Energy ◽  
Radiative Decays

Invariant amplitudes and low-energy theorems for radiative decays

1970 ◽  
Vol 66 (2) ◽  
pp. 437-448
Author(s):  
L. Burlacu ◽  
I. Raszillier
Keyword(s):  
Low Energy ◽  
Radiative Decays

INCLUSIVE WEAK RADIATIVE AND SEMILETPTONIC B DECAY

2004 ◽  
Vol 19 (31) ◽  
pp. 5513-5513
Author(s):  
MARK B. WISE
Keyword(s):  
Standard Model ◽  
Low Energy ◽  
Radiative Decays ◽  
B Decays ◽  
Weak Mixing ◽  
Theoretical Understanding ◽  
Mixing Angles ◽  
Seminal Work ◽  
Important Constraint ◽  
The Standard Model

Inclusive weak radiative and semileptonic B decays play a very important role. They are used to determine the weak mixing angles Vcb, and Vub. Furthermore the weak radiative decays provide an important constraint on extensions of the standard model, in particular low energy supersymmetry. I review the theoretical understanding of these processes with particular emphasis on the seminal work of Patrick O'Donnell.

Pole dominance calculation of πK scattering lengths

1969 ◽  
Vol 47 (23) ◽  
pp. 2715-2718
Author(s):  
C. S. Lai ◽  
D. Kiang
Keyword(s):  
Current Algebra ◽  
Present Method ◽  
Low Energy ◽  
S Waves ◽  
Pole Dominance ◽  
Meson Pole ◽  
Scattering Lengths

The low-energy πK scattering is treated within the framework of the meson pole dominance with the inclusion of nonresonant S waves. The result obtained for the πK scattering lengths in the present method is somewhat different from that of current-algebra calculation.

Low-Energy Theorem in the Radiative Decays of Charged Pions

1967 ◽  
Vol 19 (15) ◽  
pp. 859-861 ◽  
Author(s):  
T. Das ◽  
V. S. Mathur ◽  
S. Okubo
Keyword(s):  
Low Energy ◽  
Radiative Decays ◽  
Charged Pions

Dissociated Σ=27 boundaries in silicon

1988 ◽  
Vol 46 ◽  
pp. 624-625
Author(s):  
A. Garg ◽  
W.A.T. Clark ◽  
J.P. Hirth
Keyword(s):  
Electron Diffraction ◽  
Local Minimum ◽  
Boundary Energy ◽  
Coincidence Site Lattice ◽  
Boundary Plane ◽  
Low Energy ◽  
Theoretical Understanding ◽  
Site Lattice ◽  
Kikuchi Pattern ◽  
Analysis Techniques

In the last twenty years, a significant amount of work has been done in the theoretical understanding of grain boundaries. The various proposed grain boundary models suggest the existence of coincidence site lattice (CSL) boundaries at specific misorientations where a periodic structure representing a local minimum of energy exists between the two crystals. In general, the boundary energy depends not only upon the density of CSL sites but also upon the boundary plane, so that different facets of the same boundary have different energy. Here we describe TEM observations of the dissociation of a Σ=27 boundary in silicon in order to reduce its surface energy and attain a low energy configuration.The boundary was identified as near CSL Σ=27 {255} having a misorientation of (38.7±0.2)°/[011] by standard Kikuchi pattern, electron diffraction and trace analysis techniques. Although the boundary appeared planar, in the TEM it was found to be dissociated in some regions into a Σ=3 {111} and a Σ=9 {122} boundary, as shown in Fig. 1.

Transfer optics for high spatial resolution electron spectroscopy

1988 ◽  
Vol 46 ◽  
pp. 666-667
Author(s):  
G. G. Hembree ◽  
Luo Chuan Hong ◽  
P.A. Bennett ◽  
J.A. Venables
Keyword(s):  
Magnetic Field ◽  
Scanning Transmission Electron Microscope ◽  
Low Energy ◽  
Objective Lens ◽  
State University ◽  
Arizona State University ◽  
Initial Field ◽  
Resolution Electron ◽  
Scanning Transmission ◽  
Low Energy Electrons

A new field emission scanning transmission electron microscope has been constructed for the NSF HREM facility at Arizona State University. The microscope is to be used for studies of surfaces, and incorporates several surface-related features, including provision for analysis of secondary and Auger electrons; these electrons are collected through the objective lens from either side of the sample, using the parallelizing action of the magnetic field. This collimates all the low energy electrons, which spiral in the high magnetic field. Given an initial field Bi∼1T, and a final (parallelizing) field Bf∼0.01T, all electrons emerge into a cone of semi-angle θf≤6°. The main practical problem in the way of using this well collimated beam of low energy (0-2keV) electrons is that it is travelling along the path of the (100keV) probing electron beam. To collect and analyze them, they must be deflected off the beam path with minimal effect on the probe position.

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