Quantification of electron energy-loss spectra with K and L shell ionization cross-sections

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.

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Photoabsorption of hydrocarbons in Titan's atmosphere

Proceedings of the International Astronomical Union ◽

10.1017/s1743921310010914 ◽

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.

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Alternative Background Fitting for Electron Energy Loss Spectra

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100054923 ◽

1982 ◽

Vol 40 ◽

pp. 496-497

Author(s):

J. Bentley ◽

G. L. Lehman ◽

P. S. Sklad

Keyword(s):

Energy Loss ◽

Electron Energy ◽

Analytical Electron ◽

Inner Shell Ionization ◽

True Edge ◽

Integrated Intensities ◽

Electron Energy Loss ◽

Electron Excitations ◽

Electron Energy Loss Spectra ◽

Shell Ionization

Microanalysis using inner shell ionization edges in electron energy loss spectra obtained in an analytical electron microscope is now well established. In order to assess true edge profiles and obtain integrated intensities of the inner shell ionization edges of interest, it is first necessary to subtract the background. The background arises from the tails of preceding ionization edges, multiple plasmon excitations and valence electron excitations.

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Inner Shell Ionization by 60 keV Electrons, Application to Microanalysis

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100114256 ◽

1975 ◽

Vol 33 ◽

pp. 126-127

Author(s):

Y. Kihn ◽

J. Sevely ◽

B. Jouffrey

Keyword(s):

Electron Microscope ◽

Energy Loss ◽

Electron Energy ◽

Selection Rules ◽

First Approximation ◽

Inner Shell Ionization ◽

Electron Energy Loss ◽

Electron Energy Loss Spectra ◽

Shell Ionization

By using a Castaing-Henry filtering device adapted on a Siemens Elmiskop I electron microscope, we have directly observed plasmon and inner shell excitations by 60 keV electrons on electron energy loss spectra. Inner shell excitation edges have been detected up to 1900 eV.By comparing L and K inner shell excitation profiles in the case of Magnesium, Aluminium and Silicon, it is concluded that the optical selection rules, △1 = ±1, explain the shape of the spectrum after the edge in a first approximation.

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