Optical absorption spectra and crystal field analysis of Er³⁺in the cubic Cs₂NaErCl₆system

Abstract

Optical absorption spectra are reported for the 4115/2 "-9"4113/2, 4111/2, 4F9/2, 4S3/2, ~Hlx/2, 4F7/2, 4F5/2, 4F3/2, ~Gg/~ and 4Gn/2 transition regions of Er a+ in the cubic Cs~NaErCI6 system. These spectra, obtained under variable temperature conditions (2.6K to 300 K), are analysed on the basis of a crystal field model in which the Er a+ ions are assumed to reside at sites of exact octahedral (Oh) symmetry. This crystal field model is used to calculate energy levels and to calculate the magnetic dipole strengths and intensities of crystal field transition origin lines. Vibronically-induced electric dipole strengths are also calculated using a model in which the ErCI63-clusters are treated as isolated chromophoric units (uncoupled to the lattice). This latter model allows calculation of electric dipole intensities for the vibronic lines associated with the v3(t2u), v4(tlu) and v~(t~u) vibrational modes of the ErCI~ 3-cluster (the so-called moiety modes). Detailed analysis of the spectra leads to the location and assignment of all crystal field levels split out of the 4123/~, 4In~z, 4F9/~, 4Sa/2, ~Hn/2, 4F~/z, 4F5/~, 4Fa/2, 2G9/2 and 4G21/2 intermediate-coupling states, and of the three lowest-lying crystal field levels split out of the 4125/2 ground state. The best fit between the calculated and observed crystal field energy level schemes was achieved using the values of crystal field coefficients BoO) = 1608 cm -2 and B0 (6) = -195 cm -1 (defined according to the unit-tensor formalism). The most intense transitions were observed (and calculated) to be 41~512 -+4Glt/z > 4Ila12 > 2H21/z. The 4125/3 -'."4Ila/z transition region is entirely dominated by intense magnetic dipole origin lines, whereas nearly all of the intensity in the 4125/2-+4Gn/2 and ~Hn/2 transition regions is found in vibronic lines associated with the v6(85-90cm-2), v4(107-114cm -t) and v3(245-260 cm -2) ErCl~ 3-moiety modes.

Atomic tailoring of rare earth based materials for laser refrigerators

“…This crystal has several attractive features. Er concentration can be up to fully stoichiometric 16,17 , without affecting the electronic properties of the Er. This increase in the absorption is highly desirable for the laser Energy/10 3 cm -1 6.45 6.55 6.65 6.75 6.85 6.95…”

The crystal-field splitting third moment in determination of the crystal-field Hamiltonian parametrization. The cubic symmetry case

“…Finally, the obtained values of the B 40 and B 60 are compared with the available literature data. The CFPs of Refs [19] and [22] are transformed from the unit tensor operator U (k) q system to the Wybourne C (k) q one.…”

“…B 40 : 1938 [15], 2050 [21], 2059 [16], 2171 [17], 2290 [19], 2326 [18] B 60 : 236 [19], 247 [18], 250 [17], 290 [15], 290 [ [22], 1492 [15], 1494 [19], 1497 [21], 1531 [16], 1555 [20] B 60 : 140 [21], 153 [22], 154 [20], 156 [19], 160 [16], 163 [15], 174 [17]…”

Energy Transfer and Up-Conversion in the Erbium Elpasolites Cs2NaErxY1-xCl6

“…The energy levels of erbium both, as a free ion and in the elpasolite lattice, have been extensively investigated and are well catalogued [1,2]. The odd parity vibrational modes of the ErCl36+ moiety, V6, 1/4 and 1/3, occur at about 80, 120, and 280 cm -1 and are readily observed in the vibronic transitions.…”