Davis, Barry and Gervais, Benoit and McCaffrey, John G. (2018) An investigation of the sites occupied by atomic barium in solid xenon—A 2D-EE luminescence spectroscopy and molecular dynamics study. Journal of Chemical Physics, 148 (124308). ISSN 0021-9606

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Abstract

A detailed characterisation of the luminescence recorded for the 6p 1P1–6s 1S0 transition of atomic barium isolated in annealed solid xenon has been undertaken using two-dimensional excitation–emission (2D-EE) spectroscopy. In the excitation spectra extracted from the 2D-EE scans, two dominant thermally stable sites were identified, consisting of a classic, three-fold split Jahn-Teller band, labeled the blue site, and an unusual asymmetric 2 + 1 split band, the violet site. A much weaker band has also been identified, whose emission is strongly overlapped by the violet site. The temperature dependence of the luminescence for these sites was monitored revealing that the blue site has a non-radiative channel competing effectively with the fluorescence even at 9.8 K. By contrast, the fluorescence decay time of the violet site was recorded to be 4.3 ns and independent of temperature up to 24 K. The nature of the dominant thermally stable trapping sites was investigated theoretically with Diatomicsin-Molecule (DIM) molecular dynamics simulations. The DIM model was parameterized with ab initio multi-reference configuration interaction calculations for the lowest energy excited states of the Ba·Xe pair. The simulated absorption spectra are compared with the experimental results obtained from site-resolved excitation spectroscopy. The simulations allow us to assign the experimental blue feature spectrum to a tetra-vacancy trapping site in the bulk xenon fcc crystal—a site often observed when trapping other metal atoms in rare gas matrices. By contrast, the violet site is assigned to a specific 5-atom vacancy trapping site located at a grain boundary

Item Type:	Article
Additional Information:	Cite as: Davis BM, Gervais B, McCaffrey JG. An investigation of the sites occupied by atomic barium in solid xenon-A 2D-EE luminescence spectroscopy and molecular dynamics study. J Chem Phys. 2018;148(12):124308. doi:10.1063/1.5019890
Keywords:	investigation; sites occupied; atomic barium; solid xenon; 2D-EE; luminescence; spectroscopy; molecular dynamics; study;
Academic Unit:	Faculty of Science and Engineering > Chemistry
Item ID:	13102
Identification Number:	https://doi.org/10.1063/1.5019890
Depositing User:	Dr. John McCaffrey
Date Deposited:	24 Jun 2020 16:46
Journal or Publication Title:	Journal of Chemical Physics
Publisher:	American Institute of Physics
Refereed:	Yes
URI:	Publisher
Use Licence:	This item is available under a Creative Commons Attribution Non Commercial Share Alike Licence (CC BY-NC-SA). Details of this licence are available here

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