The Influence Of Matter And Black-Body Radiation Photons On The Dipole Polarizabilities A And γ Of Atoms

1996 ◽  
Vol 51 (7) ◽  
pp. 805-808 ◽  
Author(s):  
Uwe Hohm

Abstract The influence of the surroundings on the linear dipole polarizability α and second hyperpo-larizability γ is discussed in terms of the density ϱM of isotropically distributed matter as well as the density ϱp of thermal black-body radiation photons, α and γ of the rare gas atoms are studied as examples. At standard conditions, both effects are of comparable size for the rare gases. Possible consequences for ion-molecule reaction rate constants in astronomical environments are suggested.

2001 ◽  
Vol 105 (49) ◽  
pp. 11073-11079 ◽  
Author(s):  
A. Cunje ◽  
V. I. Baranov ◽  
Y. Ling ◽  
A. C. Hopkinson ◽  
D. K. Bohme
Keyword(s):  
Rare Gas ◽  

1982 ◽  
Vol 60 (7) ◽  
pp. 977-980
Author(s):  
B. Hird ◽  
S. P. Ali

Measurements of the σ10 cross section for a beam of Ar+ ions of energies between 30 and 120 keV passing through a thin target of the rare gases show good agreement with the few previous measurements in this energy region.


1994 ◽  
Vol 354 ◽  
Author(s):  
N. J. Sack ◽  
M. Akbulut ◽  
T. E. Madey

AbstractWe are investigating the transmission of low energy ions (<10 eV) through ultrathin films of condensed rare gases. Our goal is to address the issue of the depth of origin of secondary ions that desorb from solid surfaces under the impact of ionizing radiation, such as electrons, photons, or through ion sputtering. The secondary ions are produced by electron stimulated desorption (ESD) from a suitable substrate, such as an oxide or an adsórbate on a metal single crystal; the overlayer gas is condensed onto this substrate. The yield, energy and angular distributions of the ions are measured as a function of overlayer thickness. We find that 7 eV oxygen ions can be transmitted through rare gas films (Kr, Xe) several ML thick. In contrast, O+ is completely suppressed by 0.5 ML of H2O. Surprisingly, we find the F− yield to be 4 times higher in the presence of 1 ML of Xe, compared to the clean surface value, accompanied by a dramatic change in the ions’ angular distribution. We discuss a model which considers elastic scattering and charge transfer of the ions with rare gas atoms, as well as the structure of the surface and the electronic properties of the solid-vacuum interface.


2001 ◽  
Vol 664 ◽  
Author(s):  
Wolfhard Beyer

ABSTRACTThe effusion of the rare gases neon and helium, as well as of hydrogen, was studied for plasma deposited (boron-doped and undoped) hydrogenated amorphous silicon films, grown at various substrate temperatures. Rare gas atoms were incorporated into the material during the growth process or by ion implantation. The results suggest that helium and neon effusion spectra give information on the material microstructure.


1987 ◽  
Vol 41 (4) ◽  
pp. 621-624 ◽  
Author(s):  
H. B. Fannin ◽  
C. J. Seliskar ◽  
D. C. Miller

The spectral consequences of the introduction of varying concentrations of heavy rare gas atoms into a reduced-pressure helium ICP have been examined. A term-dependent quenching of He(I) emission was observed and is consistent with previous work on a kinetic model for this ICP. In addition, the ionization behavior of the added rare gases has been studied, and a simple rule seems to emerge from the results: the first ionization potential of helium represents an upper bound to the plasma energy available (probably through collisional processes) to excite and/or ionize added species. Although spectroscopic temperatures can be calculated from the state population distributions for the added neutral gas atoms, the fact that the values vary with concentration and with the chemical identity of the species betrays the fact that the plasma is not in local thermodynamic equilibrium with respect to neutral atoms. Quite differently, the results for plasma positive ions show the same statistically determined spectroscopic temperatures; thus, it appears that these ions are nearly equilibrated and also suprathermal in population distribution.


Doubly charged ions of each of the rare gases neon, argon, krypton and xenon, formed by electron impact and accelerated through 6 kV in a double-focusing mass spectrometer, are ionized to the corresponding triply charged ions via processes of at least two general kinds. The first proceeds under collision-free conditions, and can be attributed to delayed (microsecond) autoionization. An alternative explanation involving transitions from high Rydberg states, induced by the 350 K black-body radiation within the analyser vacuum housing, cannot be entirely ruled out. Other ionization processes require a collision with a molecule of collision gas, and result in a measurable loss of translational energy. In this paper the knowledge of analogous processes of the corresponding singly charged ions is reviewed, the general features of the translational energy spectra are established, and effort is devoted to the characterization of the collision-free process. The collision-induced processes have been interpreted in terms of known metastable states of the doubly charged ions.


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