Studies of autoionization with (e,2e) spectroscopy

1996 ◽  
Vol 74 (11-12) ◽  
pp. 736-742 ◽  
Author(s):  
Albert Crowe ◽  
Denis G. McDonald ◽  
Shouna E. Martin ◽  
Vsevolod V. Balashov
Keyword(s):  
Experimental Data ◽  
Electron Impact ◽  
Atomic Structure ◽  
Resonance Excitation ◽  
Resonance Ionization ◽  
Resonance States ◽  
Double Excitation ◽  
Electron Spectra ◽  
Theoretical Approaches ◽  
Rigorous Test

Recent advances in the study of double excitation-autoionization processes in helium using the (e,2e) technique are reviewed. Experiments at Flinders (Australia) and Newcastle (UK) provide the first reliable experimental data and have provoked the development of new theoretical approaches to the problem. Comparisons with recent calculations of the coincident electron spectra and parameters characterising the resonance states are presented for different kinematic conditions. Since the resonance parameters contain complex amplitudes relating to the resonance excitation, and direct and resonance ionization, they are extremely sensitive to the dynamics of the reaction and the atomic structure. Hence they provide the most rigorous test of the theory of ionization by electron impact.

Double Excitation of Helium by Electron Impact

1964 ◽  
Vol 136 (1A) ◽  
pp. A73-A86 ◽  
Author(s):  
Philip M. Becker ◽  
John S. Dahler
Keyword(s):  
Electron Impact ◽  
Double Excitation

scholarly journals The Viscosity and Atomic Structure of Volatile-Bearing Melilititic Melts at High Pressure and Temperature and the Transport of Deep Carbon

Minerals ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 267 ◽  
Author(s):  
Vincenzo Stagno ◽  
Veronica Stopponi ◽  
Yoshio Kono ◽  
Annalisa D’Arco ◽  
Stefano Lupi ◽  
...  
Keyword(s):  
Experimental Data ◽  
High Pressure ◽  
Atomic Structure ◽  
Ex Situ ◽  
X Ray Diffraction ◽  
High Pressure And Temperature ◽  
X Ray ◽  
Falling Sphere ◽  
Basaltic Melts

Understanding the viscosity of mantle-derived magmas is needed to model their migration mechanisms and ascent rate from the source rock to the surface. High pressure–temperature experimental data are now available on the viscosity of synthetic melts, pure carbonatitic to carbonate–silicate compositions, anhydrous basalts, dacites and rhyolites. However, the viscosity of volatile-bearing melilititic melts, among the most plausible carriers of deep carbon, has not been investigated. In this study, we experimentally determined the viscosity of synthetic liquids with ~31 and ~39 wt% SiO2, 1.60 and 1.42 wt% CO2 and 5.7 and 1 wt% H2O, respectively, at pressures from 1 to 4.7 GPa and temperatures between 1265 and 1755 °C, using the falling-sphere technique combined with in situ X-ray radiography. Our results show viscosities between 0.1044 and 2.1221 Pa·s, with a clear dependence on temperature and SiO2 content. The atomic structure of both melt compositions was also determined at high pressure and temperature, using in situ multi-angle energy-dispersive X-ray diffraction supported by ex situ microFTIR and microRaman spectroscopic measurements. Our results yield evidence that the T–T and T–O (T = Si,Al) interatomic distances of ultrabasic melts are higher than those for basaltic melts known from similar recent studies. Based on our experimental data, melilititic melts are expected to migrate at a rate ~from 2 to 57 km·yr−1 in the present-day or the Archaean mantle, respectively.

Electron-impact helium double excitation within the S-wave model

2004 ◽  
Vol 37 (18) ◽  
pp. 3711-3721 ◽  
Author(s):  
C Plottke ◽  
P Nicol ◽  
I Bray ◽  
D V Fursa ◽  
A T Stelbovics
Keyword(s):  
Electron Impact ◽  
Wave Model ◽  
S Wave ◽  
Double Excitation

The inner shell ionization of atoms by electron impact

1940 ◽  
Vol 36 (1) ◽  
pp. 43-52 ◽  
Author(s):  
E. H. S. Burhop ◽  
H. S. W. Massey
Keyword(s):  
Experimental Data ◽  
Electron Impact ◽  
Cross Section ◽  
Nickel Silver ◽  
Inner Shell Ionization ◽  
Good For ◽  
The Cross ◽  
Shell Ionization ◽  
Good Agreement

Calculations have been made of the cross-section for ionization of the inner shells of atoms by electron impact in the cases of the K-shells of nickel, silver, mercury and of the three L-shells of silver and mercury.The agreement with experiment is reasonably good for the K-shell ionization, but only fair in the case of the rather meagre experimental data available for the L-shell. The values obtained for the relative ionization in the K- and L-shells are in good agreement with those to be expected from experiment.

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