In situ formation and characterisation of singly ionised atomic europium in rare gas matrices—Luminescence spectroscopy and MP2 calculations

Abstract

Irradiation of atomic europium isolated in the solid rare gases, with low intensity laser excitation of the y 8 P ← a 8 S 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 4f 7 ( 8 S 7/2 )6p 3/2 absorption bands of Eu + between 390 and 410 nm produces emission which is quite distinct from that resulting from excitation of the 4f 7 ( 8 S 7/2 )6p 1/2 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 p 3/2 and p 1/2 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 (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. C 2015 AIP Publishing LLC. [http://dx

Absorption spectroscopy of heavy alkaline earth metals Ba and Sr in rare gas matrices—CCSD(T) calculations and atomic site occupancies

“…In contrast to our recent Eu/RG work, 37 which demonstrated the production of matrix-isolated Eu cations after laser irradiation, the Ba/RG matrices prepared in this work do not contain any Ba ions in the samples prepared either by thermal vaporisation or e-bombardment. Several of the bands attributed to "candidate" Ba ions in the recent Ba/Ar and Ba/Xe matrix work published in Ref.…”

Heat- and light-induced transformations of Yb trapping sites in an Ar matrix

“…The data obtained by thermal deposition of Yb atoms by our group are compared to that obtained by ablation deposition techniques in previously published works. 10 The matrix-isolated Eu atom, which differs from the Yb atom in its 4f shell occupation (7 unpaired electrons vs. 14 paired ones), has been thoroughly investigated by Byrne and McCaffrey 8,9,37 and offers an interesting point of comparison. In solid Ar, Eu was found to occupy two stable trapping sites, "red" and "blue," with mean frequency shifts of 760 and 1350 cm −1 , respectively, in the 6s 2 8 S → 6s6p y 8 P transition.…”