Byrne, Owen and Davis, Gary and McCaffrey, John G.
(2015)
In situ formation and characterisation of singly ionised atomic europium in rare gas matrices-Luminescence spectroscopy and MP2 calculations.
Journal of Chemical Physics, 142.
054307.
ISSN 0021-9606
Abstract
Irradiation of atomic europium isolated in the solid rare gases, with low intensity laser excitation of
the y8P ← a8S resonance transition at ca. 465 nm, is found to produce singly charged europium
cations (Eu+) in large amounts in xenon and in smaller amounts in argon. Confirmation of the
formation of matrix-isolated Eu+ is obtained from characteristic absorption bands in the UV and in the
visible spectral regions. The luminescence produced with excitation of the cation bands is presented
in greatest detail for Eu/Xe and assigned. Excitation of the 4f7(8S7/2)6p3/2 absorption bands of Eu+
between 390 and 410 nm produces emission which is quite distinct from that resulting from excitation
of the 4f7(8S7/2)6p1/2 absorption (430 to 450 nm) features. The latter consists of narrow, resolved
emission bands with Stokes shifts ten times smaller than the former. The observed spectral differences
are discussed in relation to the different spatial symmetries of the p3/2 and p1/2 orbitals in these j-j
coupled (7/2, 3/2)J and the (7/2, 1/2)J levels. Møller-Plesset calculations are conducted to obtain the
molecular parameters of the neutral Eu-RG and cationic Eu+-RG diatomics (RG = Ar, Kr, Xe). From
the short bond lengths and the strong binding energies obtained for the Eu+-RG species, these values
suggest the isolation of the ion in small, possibly interstitial sites especially in xenon. In contrast, but
consistent with previous work [O. Byrne and J. G. McCaffrey, J. Chem. Phys. 134, 124501 (2011)],
the interaction potentials calculated herein for the Eu-RG diatomics suggest that the neutral Eu atom
occupies tetra-vacancy (tv) and hexa-vacancy (hv) sites in the solid rare gas hosts. Possible reasons
for the facile production of Eu+ in the solid rare gases are discussed. The mechanism proposed is that
atomic europium is also acting as an electron acceptor, providing a temporary trap for the ionised
electron in the matrices.
| Item Type: |
Article
|
| Keywords: |
atomic europium; rare gas matrices; Luminescence spectroscopy; MP2 calculations; |
| Academic Unit: |
Faculty of Science and Engineering > Chemistry |
| Item ID: |
7773 |
| Identification Number: |
https://doi.org/10.1063/1.4907201 |
| Depositing User: |
Dr. John McCaffrey
|
| Date Deposited: |
17 Jan 2017 14:38 |
| Journal or Publication Title: |
Journal of Chemical Physics |
| Publisher: |
American Institute of Physics |
| Refereed: |
Yes |
| URI: |
|
| 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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