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Investigations of the Optical Spectroscopy of Atomic Sodium Isolated in Solid Argon and Krypton: Experiments and Simulations

Ryan, Maryanne and Collier, Martin and de Pujo, Patrick and Crepin, Claudine and McCaffrey, John G. (2010) Investigations of the Optical Spectroscopy of Atomic Sodium Isolated in Solid Argon and Krypton: Experiments and Simulations. Journal of Physical Chemistry A, 114 (9). pp. 3011-3024. ISSN 1089-5639

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Abstract

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.

Item Type: Article
Additional Information: 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.
Keywords: Optical Spectroscopy; Atomic Sodium; Solid Argon; Krypton; Experiments; Simulations; Rare gases;
Subjects: Science & Engineering > Chemistry
Item ID: 2652
Identification Number: DOI: 10.1021/jp905596a
Depositing User: Dr. John McCaffrey
Date Deposited: 25 Aug 2011 09:07
Journal or Publication Title: Journal of Physical Chemistry A
Publisher: American Chemical Society
Refereed: Yes
URI:

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