Trajectory and charge dependence of L x-ray fluorescence following Ar/sup +/+Ar collisions

Journal Article · Mon Feb 01 04:00:00 EST 1982 · Phys. Rev. A; (United States)

DOI:https://doi.org/10.1103/PhysRevA.25.816· OSTI ID:5525637

Thomson, G M

The coincidence technique has been employed to determine the yield of L x-rays emitted following Ar/sup +/+Ar collisions of known incident energy T/sub 0/, scattering angle theta = 14/sup 0/, and scattered ion charge m. The range of T/sub 0/ studied, 50 to 575 keV, corresponds to a distance of closest internuclear separation r/sub 0/ from 0.18 to 0.03 A. As in the case of our earlier Auger-electron coincidence experiments on Ar/sup +/+Ar over this range, the present work uncovers evidence for two different L-vacancy-creating processes. The first process has a threshold at r/sub 0/ = 0.25 A and is the result of the transfer of two electrons out of the 4fsigma molecular orbital (MO). The second process, which appears when r/sub 0/ is made less than 0.13 A, is due to rotational transitions of up to six electrons from the 3d..pi.. and 3dsigma MO's into the 3ddelta MO. We find that there is a large increase in x-ray fluorescence associated with the 3d..pi.., 3dsigma..-->..3ddelta transition, an increase which is considerably in excess of that expected from available estimates. A qualitative explanation of this phenomenon is offered that takes into account combinations of long-lived autoionizing states involving outer-shell electrons, preferential pumping of L electrons up to the 3d radiative level, and finally, outer-shell-electron depopulation by prior Auger transitions. This interpretation is also consistent with the differing ion-charge x-ray-yield correlations that we find are characteristic of the 4fsigma and 3d..pi..,3dsigma processes.

• Research Organization: U.S. Army Ballistic Research Laboratory, ARRADCOM, Aberdeen Proving Ground, Maryland 21005
• OSTI ID: 5525637
• Journal Information: Phys. Rev. A; (United States), Journal Name: Phys. Rev. A; (United States) Vol. 25:2; ISSN PLRAA
• Country of Publication: United States
• Language: English

Related Subjects

640304* -- Atomic
Molecular & Chemical Physics-- Collision Phenomena
74 ATOMIC AND MOLECULAR PHYSICS
ARGON
ARGON IONS
ATOM COLLISIONS
AUGER EFFECT
AUTOIONIZATION
CHARGED PARTICLES
COINCIDENCE METHODS
COLLISIONS
COUNTING TECHNIQUES
ELECTROMAGNETIC RADIATION
ELEMENTS
ENERGY RANGE
FLUIDS
FLUORESCENCE
GASES
ION COLLISIONS
ION-ATOM COLLISIONS
IONIZATION
IONIZING RADIATIONS
IONS
KEV RANGE
KEV RANGE 10-100
KEV RANGE 100-1000
LUMINESCENCE
NONMETALS
RADIATIONS
RARE GASES
X RADIATION