ChemInform Abstract: Electron Transmission and Inner-Shell Electron Energy Loss Spectroscopy of CH3CN, CH3NC, CH3SCN, and CH3NCS.

ChemInform ◽  
1989 ◽  
Vol 20 (31) ◽  
Author(s):  
A. P. HITCHCOCK ◽  
M. TRONC ◽  
A. MODELLI
Keyword(s):  
Energy Loss ◽  
Electron Energy ◽  
Electron Energy Loss Spectroscopy ◽  
Electron Transmission ◽  
Shell Electron ◽  
Electron Energy Loss

An examination of centrifugal barrier effects in iodine pentafluoride by inner shell electron energy loss spectroscopy

1994 ◽  
Vol 72 (11-12) ◽  
pp. 1093-1100
Author(s):  
Glyn Cooper ◽  
Wenzhu Zhang ◽  
C. E. Brion
Keyword(s):  
Energy Loss ◽  
Electron Energy ◽  
Electron Energy Loss Spectroscopy ◽  
Shape Resonance ◽  
High Electron ◽  
Excitation Spectra ◽  
Experimental Conditions ◽  
Barrier Effects ◽  
Shell Electron ◽  
Electron Energy Loss

Electron energy loss spectroscopy was used to study the core (I 4d, I 3d, and F Is) level electronic excitation spectra of IF5. The spectra were collected under experimental conditions such that dipole transitions were dominant (high electron impact energy (3 keV) and 0° scattering angle). The spectra were assigned using term value arguments, and by analogy with those of the isoelectronic molecules TeF6 and XeF4. In common with the spectra of TeF6 and XeF4, the spectra of IF5 show features that are consistent with a centrifugal potential-barrier model. In particular, transitions to virtual valence orbitals and to above-edge shape resonance channels are relatively intense, whereas transitions to Rydberg orbitals are, in comparison, very weak or absent. As in the case of TeF6, it was necessary to include atomic 4f orbitals in the molecular orbital basis to adequately account for the continuum resonance features observed in the IF5 spectra. The valence shell electron energy loss spectrum of IF5 from 5 to 35 eV was also obtained.

scholarly journals The σ* molecular orbitals of perfluoroalkanes as studied by inner-shell electron energy loss and electron transmission spectroscopies

1988 ◽  
Vol 66 (8) ◽  
pp. 2104-2121 ◽  
Author(s):  
I. Ishii ◽  
R. McLaren ◽  
A. P. Hitchcock ◽  
K. D. Jordan ◽  
Y. Choi ◽  
...  
Keyword(s):  
Energy Loss ◽  
Electron Energy ◽  
Inductive Effect ◽  
Oscillator Strengths ◽  
Negative Ion ◽  
Electron Transmission ◽  
Ultraviolet Excitation ◽  
Shell Electron ◽  
Electron Energy Loss ◽  
Electron Energy Loss Spectra

Absolute oscillator strength spectra in the C 1s (280–340 eV) and F 1s (680–740 eV) regions of the perfluoro-n-alkanes from C2 to C6 and perfluorocycloalkanes from C3 to C6 have been determined from inner-shell electron energy loss spectra recorded under electric-dipole scattering conditions. The spectral features are interpreted in terms of spatially localized transitions terminating at orbitals of predominantly σ*(C—F) and σ*(C—C) character. When compared to the spectra of the perfluoro-n-alkanes, both the C 1s and F 1s spectra of the perfluorocycloalkanes exhibit additional low-lying bands which are assigned to transitions terminating at σ*(C—C) orbitals which are shifted to low energy by the combination of the strain of cyclization and the inductive effect of the fluorination. The electron transmission spectra of selected perfluorocycloalkanes (which provide information on their anion states) show as well that the electron affinities of the cyclic systems are substantially lower than those of the corresponding perfluoro-n-alkanes, again as a result of a low-lying σ* orbital in the cyclic species. Quantum chemical calculations of the alkane and perfluoroalkane ground-state orbital structures support the experimental results. The localized character of the inner-shell excitations, indicated by the constancy of both term values and oscillator strengths with increasing chain length, contrasts with the more delocalized character of the states accessed in ultraviolet excitation or negative ion formation.

Data Acquisition and Handling Unit for a Quantitative Use of Electron Energy Loss Spectroscopy

1977 ◽  
Vol 35 ◽  
pp. 232-233 ◽  
Author(s):  
P. Trebbia ◽  
P. Ballongue ◽  
C. Colliex
Keyword(s):  
Electron Microscope ◽  
Energy Loss ◽  
Electron Energy ◽  
Electron Energy Loss Spectroscopy ◽  
Single Channel ◽  
Detection System ◽  
Surface Barrier ◽  
Solid State Detector ◽  
Electrostatic Mirror ◽  
Electron Energy Loss

An effective use of electron energy loss spectroscopy for chemical characterization of selected areas in the electron microscope can only be achieved with the development of quantitative measurements capabilities.The experimental assembly, which is sketched in Fig.l, has therefore been carried out. It comprises four main elements.The analytical transmission electron microscope is a conventional microscope fitted with a Castaing and Henry dispersive unit (magnetic prism and electrostatic mirror). Recent modifications include the improvement of the vacuum in the specimen chamber (below 10-6 torr) and the adaptation of a new electrostatic mirror.The detection system, similar to the one described by Hermann et al (1), is located in a separate chamber below the fluorescent screen which visualizes the energy loss spectrum. Variable apertures select the electrons, which have lost an energy AE within an energy window smaller than 1 eV, in front of a surface barrier solid state detector RTC BPY 52 100 S.Q. The saw tooth signal delivered by a charge sensitive preamplifier (decay time of 5.10-5 S) is amplified, shaped into a gaussian profile through an active filter and counted by a single channel analyser.

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