A high sensitivity momentum dispersive multichannel electron momentum spectrometer for studies in experimental quantum chemistry

1994 ◽  
Vol 65 (2) ◽  
pp. 349-358 ◽  
Author(s):  
B. R. Todd ◽  
N. Lermer ◽  
C. E. Brion
Keyword(s):  
Quantum Chemistry ◽  
High Sensitivity ◽  
Electron Momentum

A high sensitivity electron momentum spectrometer with simultaneous detection in energy and momentum

2002 ◽  
Vol 73 (6) ◽  
pp. 2242-2248 ◽  
Author(s):  
Masahiko Takahashi ◽  
Taku Saito ◽  
Motoaki Matsuo ◽  
Yasuo Udagawa
Keyword(s):  
Simultaneous Detection ◽  
High Sensitivity ◽  
Electron Momentum ◽  
Energy And Momentum

A high-sensitivity angle and energy dipersive multichannel electron momentum spectrometer with 2πangle range

2011 ◽  
Vol 82 (3) ◽  
pp. 033110 ◽  
Author(s):  
QiGuo Tian ◽  
KeDong Wang ◽  
Xu Shan ◽  
XiangJun Chen
Keyword(s):  
High Sensitivity ◽  
Electron Momentum

(e, 2e) electron momentum spectrometer with high sensitivity and high resolution

2005 ◽  
Vol 76 (6) ◽  
pp. 063103 ◽  
Author(s):  
X. G. Ren ◽  
C. G. Ning ◽  
J. K. Deng ◽  
S. F. Zhang ◽  
G. L. Su ◽  
...  
Keyword(s):  
High Resolution ◽  
High Sensitivity ◽  
Electron Momentum

Insights into theoretical quantum chemistry from electron momentum spectroscopy

1996 ◽  
Vol 74 (11-12) ◽  
pp. 757-762 ◽  
Author(s):  
Ernest R. Davidson
Keyword(s):  
Hydrogen Bond ◽  
Wave Function ◽  
Binding Energy ◽  
Quantum Chemistry ◽  
Excited States ◽  
Momentum Density ◽  
Water Dimer ◽  
Basis Sets ◽  
Electron Momentum ◽  
Electron Momentum Spectroscopy

Most basis sets used in quantum chemistry are designed to get the correct charge and momentum density in the region important for covalent bonding. The (e,2e) cross section measured by electron momentum spectroscopy (EMS) emphasizes the low-momentum, large r, region of the wave function. Improving the description of this part of the wave function for water has resulted in good agreement with (e,2e) data. Because the hydrogen bond is sensitive to the long-range tail of the wave function, this has simultaneously led to an improved description of the hydrogen bond in the water dimer. The satellite region of the binding energy spectrum gives information about the excited states of the cation that is not available at present from any other form of spectroscopy. Calculations seeking agreement with the binding-energy spectra and the momentum distribution associated with satellite peaks have led to the most complete catalog of the cation excited states for ethylene. Here we report the assignment of the excited states based on the dominant part of the wave function rather than focusing on the small coefficients that describe the intensity borrowing from the primary holes. We also examine the adequacy of the assumption that every Dyson orbital is similar to one of the Hartree–Fock orbitals.

Radio Measurements of Coronal Magnetic Fields

1994 ◽  
Vol 144 ◽  
pp. 21-28 ◽  
Author(s):  
G. B. Gelfreikh
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Solar Corona ◽  
Active Regions ◽  
High Sensitivity ◽  
Coronal Magnetic Field ◽  
Transverse Magnetic ◽  
Radio Sources ◽  
Radio Waves ◽  
Solar Active Regions

AbstractA review of methods of measuring magnetic fields in the solar corona using spectral-polarization observations at microwaves with high spatial resolution is presented. The methods are based on the theory of thermal bremsstrahlung, thermal cyclotron emission, propagation of radio waves in quasi-transverse magnetic field and Faraday rotation of the plane of polarization. The most explicit program of measurements of magnetic fields in the atmosphere of solar active regions has been carried out using radio observations performed on the large reflector radio telescope of the Russian Academy of Sciences — RATAN-600. This proved possible due to good wavelength coverage, multichannel spectrographs observations and high sensitivity to polarization of the instrument. Besides direct measurements of the strength of the magnetic fields in some cases the peculiar parameters of radio sources, such as very steep spectra and high brightness temperatures provide some information on a very complicated local structure of the coronal magnetic field. Of special interest are the results found from combined RATAN-600 and large antennas of aperture synthesis (VLA and WSRT), the latter giving more detailed information on twodimensional structure of radio sources. The bulk of the data obtained allows us to investigate themagnetospheresof the solar active regions as the space in the solar corona where the structures and physical processes are controlled both by the photospheric/underphotospheric currents and surrounding “quiet” corona.

Backscattered Electron Imaging of GaAs/AlGaAs Super Lattice Structures with an Ultra-High- Resolution SEM

1988 ◽  
Vol 46 ◽  
pp. 204-205
Author(s):  
Kazumichi Ogura ◽  
Michael M. Kersker
Keyword(s):  
High Resolution ◽  
Layer Structure ◽  
High Sensitivity ◽  
Beam Current ◽  
Electron Beam Current ◽  
Lattice Structures ◽  
Super Lattice ◽  
Different Types ◽  
Backscattered Electron ◽  
Electron Imaging

Backscattered electron (BE) images of GaAs/AlGaAs super lattice structures were observed with an ultra high resolution (UHR) SEM JSM-890 with an ultra high sensitivity BE detector. Three different types of super lattice structures of GaAs/AlGaAs were examined. Each GaAs/AlGaAs wafer was cleaved by a razor after it was heated for approximately 1 minute and its crosssectional plane was observed.First, a multi-layer structure of GaAs (100nm)/AlGaAs (lOOnm) where A1 content was successively changed from 0.4 to 0.03 was observed. Figures 1 (a) and (b) are BE images taken at an accelerating voltage of 15kV with an electron beam current of 20pA. Figure 1 (c) is a sketch of this multi-layer structure corresponding to the BE images. The various layers are clearly observed. The differences in A1 content between A1 0.35 Ga 0.65 As, A1 0.4 Ga 0.6 As, and A1 0.31 Ga 0.69 As were clearly observed in the contrast of the BE image.

An x-ray microprobe based upon a close-coupled focal-spot / glass capillary arrangement

1992 ◽  
Vol 50 (2) ◽  
pp. 1758-1759
Author(s):  
D. A. Carpenter ◽  
M. A. Taylor
Keyword(s):  
Imaging Techniques ◽  
Fluorescence Analysis ◽  
High Sensitivity ◽  
Specimen Preparation ◽  
X Rays ◽  
Glass Capillary ◽  
Close Coupling ◽  
X Ray ◽  
Point To Point ◽  
Beam Damage

The development of intense sources of x rays has led to renewed interest in the use of microbeams of x rays in x-ray fluorescence analysis. Sparks pointed out that the use of x rays as a probe offered the advantages of high sensitivity, low detection limits, low beam damage, and large penetration depths with minimal specimen preparation or perturbation. In addition, the option of air operation provided special advantages for examination of hydrated systems or for nondestructive microanalysis of large specimens.The disadvantages of synchrotron sources prompted the development of laboratory-based instrumentation with various schemes to maximize the beam flux while maintaining small point-to-point resolution. Nichols and Ryon developed a microprobe using a rotating anode source and a modified microdiffractometer. Cross and Wherry showed that by close-coupling the x-ray source, specimen, and detector, good intensities could be obtained for beam sizes between 30 and 100μm. More importantly, both groups combined specimen scanning with modern imaging techniques for rapid element mapping.

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