Differential cross sections for plasmon excitations and reflected electron-energy-loss spectra

1994 ◽  
Vol 49 (23) ◽  
pp. 16684-16693 ◽  
Author(s):  
C. J. Tung ◽  
Y. F. Chen ◽  
C. M. Kwei ◽  
T. L. Chou
Keyword(s):  
Energy Loss ◽  
Electron Energy ◽  
Cross Sections ◽  
Differential Cross ◽  
Differential Cross Sections ◽  
Electron Energy Loss ◽  
Electron Energy Loss Spectra

scholarly journals Deconvolution of Overlapping Features in Electron Energy-loss Spectra: Determination of Absolute Differential Cross Sections for Electron-impact Excitation of Electronic States of Molecules

1997 ◽  
Vol 50 (3) ◽  
pp. 525 ◽  
Author(s):  
L. Campbell ◽  
P. J. O. Teubner ◽  
M. J. Brunger ◽  
B. Mojarrabi ◽  
D. C. Cartwright
Keyword(s):  
Energy Loss ◽  
Electron Energy ◽  
Cross Sections ◽  
Differential Cross ◽  
Electronic States ◽  
Impact Excitation ◽  
Spectroscopic Constants ◽  
Differential Cross Sections ◽  
Electron Energy Loss ◽  
Electron Energy Loss Spectra

A set of three computer programs is reported which allow for the deconvolution of overlapping molecular electronic state structure in electron energy-loss spectra, even in highly perturbed systems. This procedure enables extraction of absolute differential cross sections for electron-impact excitation of electronic states of diatomic molecules from electron energy-loss spectra. The first code in the sequence uses the Rydberg–Klein–Rees procedure to generate potential energy curves from spectroscopic constants, and the second calculates Franck–Condon factors by numerical solution of the Schrödinger equation, given the potential energy curves. The third, given these Franck–Condon factors, the previously calculated relevant energies for the vibrational levels of the respective electronic states (relative to the v″ = 0 level of the ground electronic state) and the experimental energy-loss spectra, extracts the differential cross sections for each state. Each program can be run independently, or the three can run in sequence to determine these cross sections from the spectroscopic constants and the experimental energy-loss spectra. The application of these programs to the specific case of electron scattering from nitric oxide (NO) is demonstrated.

scholarly journals Photoabsorption of hydrocarbons in Titan's atmosphere

2009 ◽  
Vol 5 (H15) ◽  
pp. 678-679
Author(s):  
Fabíola P. Magalhães ◽  
Gerardo G. B. de Souza ◽  
Heloisa M. Boechat-Roberty
Keyword(s):  
Energy Loss ◽  
Absorption Spectra ◽  
Electron Energy ◽  
Cross Sections ◽  
Molecular Species ◽  
Uv Absorption ◽  
Synthetic Spectrum ◽  
Uv Absorption Spectra ◽  
Electron Energy Loss ◽  
Electron Energy Loss Spectra

AbstractTitan, the largest satellite of the planet Saturn, has a thick atmosphere which consists of nitrogen (N2) and methane (CH4). In 2004, the Cassini-Huygens mission observed the occultation of two stars through the atmosphere of Titan and measured ultraviolet (UV) absorption spectra. Through these spectra it was possible to identify the molecular species contained in this environment. In the present work, we have simulated a spectrum of this atmosphere using some molecules such as CH4, C2H2, C2H4, C2H6, C4H2, and C6H6. Our cross sections data were experimentally obtained using the electron energy-loss technique, where the electron energy-loss spectra, measured high incident energies and in small scattering angles, are similar to photoabsorption spectra. The comparison of our synthetic spectrum with that measured by Cassini shows that this method is very efficient for identifying molecules as well as estimating abundances.

Parallel Detection of Electron Energy Loss Spectra in Direct Mode

1990 ◽  
Vol 48 (2) ◽  
pp. 82-83
Author(s):  
Eckhard Quandt ◽  
Stephan laBarré ◽  
Andreas Hartmann ◽  
Heinz Niedrig
Keyword(s):  
Energy Loss ◽  
Electron Energy ◽  
Energy Resolution ◽  
Large Angle ◽  
Maximum Energy ◽  
Semiconductor Detectors ◽  
Parallel Detection ◽  
Photodiode Arrays ◽  
Electron Energy Loss ◽  
Electron Energy Loss Spectra

Due to the development of semiconductor detectors with high spatial resolution -- e.g. charge coupled devices (CCDs) or photodiode arrays (PDAs) -- the parallel detection of electron energy loss spectra (EELS) has become an important alternative to serial registration. Using parallel detection for recording of energy spectroscopic large angle convergent beam patterns (LACBPs) special selected scattering vectors and small detection apertures lead to very low intensities. Therefore the very sensitive direct irradiation of a cooled linear PDA instead of the common combination of scintillator, fibre optic, and semiconductor has been investigated. In order to obtain a sufficient energy resolution the spectra are optionally magnified by a quadrupole-lens system.The detector used is a Hamamatsu S2304-512Q linear PDA with 512 diodes and removed quartz-glas window. The sensor size is 13 μm ∗ 2.5 mm with an element spacing of 25 μm. Along with the dispersion of 3.5 μm/eV at 40 keV the maximum energy resolution is limited to about 7 eV, so that a magnification system should be attached for experiments requiring a better resolution.

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