8:00 AM–10:48 AM, Wednesday, March 12, 2008
Morial Convention Center - 228
Sponsoring Unit:
GIMS
Chair: George Srajer, Argonne National Laboratory
Abstract ID: BAPS.2008.MAR.P36.7
9:36 AM–9:48 AM
Peter Abbamonte
(University of Illinois)
Wei Ku
(Brookhaven National Laboratory)
Tim Graber
(University of Chicago)
James Reed
(University of Illinois)
Serban Smadici
(University of Illinois)
Abhay Shukla
(Universite Pierre et Marie Curie)
Jean-Pascal Rueff
(Synchrotron SOLIEL)
We have used inelastic x-ray scattering, coupled with recently developed inversion techniques, to reconstruct the structure and dynamics of the valence exciton in the prototype alkali halide LiF. Our inversions, which yield resolutions $\Delta x = 0.533 \AA$ and $\Delta t = 20.67 as (2.067 \times 10^{-17} s)$, reveal that the exciton forms in less than $50 as$, oscillates with a period of $283 as$, and decays after approximately $5 fs$. It contains a pronounced $a/3$ internal periodicity, where $a = 4.027 \AA$ is the crystal lattice parameter, that changes little during the course of its life, indicating that this exciton lies very close to the Frenkel limit. Our results resolve a 70 year old contraversy about the valence exciton in alkali halides and, when compared to {\it ab initio} calculations, demonstrate a simplified theoretical approach to describing excitons in the limit of strong binding energy.
To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2008.MAR.P36.7