Study of inner-shell vacancy cascades by coincidence techniques

Technical Report · Tue Aug 01 04:00:00 EDT 1995

DOI:https://doi.org/10.2172/166504· OSTI ID:166504

LeBrun, T.; Arp, U.; MacDonald, M.; Southworth, S. H.

An inner-shell vacancy in an atom decays by an intricate combination of Auger and fluorescence processes. The interrelation between these processes is not well understood because traditional studies of core-excited atoms focus on only one of the many particles that participate in the relaxation - largely ignoring the other components and the correlations between them. To understand these correlations we developed a coincidence technique that uses coincident detection of X-rays and electrons to select decay pathways that involve emission of both an X-ray photon and electrons. In the first application of this technique, the Ar 1s photoelectron spectrum was recorded selectively in coincidence with X-ray fluorescence to eliminate the asymmetric broadening and shifting of the energy distribution which results due to post-collision interaction with K-Auger electrons. This allowed the direct observation of the interaction between the photoelectron and the decay of core holes created after the initial photoionization event. We have also applied this technique to the much more complex problem of understanding Auger-electron spectra produced by vacancy cascades following inner-shell excitation. For example, we previously recorded non-coincident electron spectra of L{sub 2,3}MM Auger transitions following K-shell excitation of argon. Interpretation of these spectra is difficult because they are complicated and consist of many overlapping or unresolved Auger transitions between different ionic states.

• Research Organization: Argonne National Lab., IL (United States)
• OSTI ID: 166504
• Report Number(s): ANL--95/14; ON: DE96000985
• Country of Publication: United States
• Language: English

Related Subjects

44 INSTRUMENTATION
INCLUDING NUCLEAR AND PARTICLE DETECTORS
66 PHYSICS
COINCIDENCE METHODS
INNER-SHELL EXCITATION
PHOTOIONIZATION
PROGRESS REPORT
X-RAY FLUORESCENCE ANALYSIS