Ryan, Maryanne and Collier, Martin and de Pujo, Patrick and Crepin, Claudine and McCaffrey, John G.
Investigations of the Optical Spectroscopy of Atomic Sodium Isolated in Solid Argon and
Krypton: Experiments and Simulations.
Journal of Physical Chemistry A, 114 (9).
The absorption spectra of thin film samples, formed by the codeposition of sodium vapor with the rare gases
have long been known to consist of complex structures in the region of the atomic sodium “yellow-doublet”
lines. The photophysical characteristics of the associated luminescence (excitation/emission) spectra, indicate
strong interaction between the excited P state Na atom and the rare gases (Ar, Kr, and Xe) used as host
solids. This system is reinvestigated with new experimental spectroscopic results and molecular dynamics
(MD) calculations. The so-called “violet” site in Ar and Kr has been produced by laser excitation of thermally
deposited samples. The simulation of the “spray-on” deposition of thin films enables identification of
tetravacancy (tv) sites of isolation for ground-state atomic sodium in Ar while in Kr this site is found in
addition to single vacancy (sv) occupancy. Various cubic symmetry sites were taken into account to simulate
absorption and emission spectra using accurate interaction potentials for the Na ·RG diatomics. The wellknown
3-fold splitting in absorption, attributed to the Jahn-Teller effect, was very well reproduced but the
simulated spectra for all the sites considered are located in the low energy region of the experimental bands.
The evolution of the excited state Na atom is followed revealing the nature and symmetry of the sites that are
transiently occupied. Consistent with the large Stokes shift observed experimentally, there is an extensive
rearrangement of the lattice in the excited state with respect to the ground state. Combining all the experimental
and theoretical information, an assignment of experimental violet, blue, and red absorption features is established
involving single vacancy, tetravacancy, and hexavacancy sites, respectively, in Ar and Kr.
||Fruitful discussions with Dr. Benoit
Gervais are kindly acknowledged. This work was supported in
part by the Irish Government Embark Initiative (IRCSET)
programme Grant. In addition, J.McC. gratefully acknowledges
Prof. invitee positions at Universite Paris Sud 11 (hosted by
Dr. C. Crépin) which commenced this work and recently at
Universite Pierre et Marie Curie, Jussieu (hosted by Prof. L.
Krim) which concluded this work.
||Optical Spectroscopy; Atomic Sodium; Solid Argon; Krypton; Experiments; Simulations; Rare gases;
||Faculty of Science and Engineering > Chemistry
Dr. John McCaffrey
||25 Aug 2011 09:07
|Journal or Publication Title:
||Journal of Physical Chemistry A
||American Chemical Society
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