Vibronic Spectra and the Dynamic Jahn‐Teller Effect of Cubic ZnS:Cu²⁺

Abstract

Near infrared absorption and emission spectra due to the transitions ZT,of the Cu2+ ion in cubic ZnS have been measured a t 4K. The distinct vibronic sidebands of the absorption spectrum exactly correspond to various critical point energies of TA, TO, and LO lattice modes, whereas the structure of the luminescence spectrum cannot be interpreted in terms of lattice phonon satellites. A dynamic Jahn-Teller interaction in the ,T2 ground state being in the same order of magnitude as static lattice spin-orbit splitting and phonon energy is shown to produce this deviation from the mirror symmetry. Weak and strong coupling approximations in the cluster limit have been extended t o include vibronic states with up to six E-modes.Absorptions-und Emissions-Spektren im nahen Infrarot hervorgerufen , durch die Ubergange 2T, -,E des Cu2+ in kubischem ZnS, wurden bei 4 K aufgenommen. Die ausgepragten vibronischen Seitenbanden des Absorptionsspektrums entsprechen exakt den Energien verschiedener kritischer Punkte der TA-, TO-und LO-Gittermoden, wahrend das Emissionsspektrum nicht durch Phononenenergien des ungestorten Gitters zu erklaren ist. Es wird gezeigt, da13 eine dynamische Jahn-Teller-Wechselwirkung im 2T,-Grundzustand von der GroBenordnung der statischen Spin-Bahn-Aufspaltung und Phononenenergie diese Abweichung von der Spiegelsymmetrie hervorruft. Die Naherungen schwacher und starker Kopplung im Cluster-Mode11 werden auf vibronische Zustande mit bis zu sechs E-Moden ausgedehnt.

Dynamic Jahn-Teller effect in crystals doped with 3d ions

“…Among the 3d transition metals, Cu 2+ has one of the most simple electron system for testing theoretical approximations. Infrared spectra have been reported for Cu 2+ in 1) ZnO [164], 2) ZnS [165,166], 3) CdS [165,167], and 4) CdTe [168]. The experimental observations in these system show evidence of dynamic JT effects in the intermediate coupling limit.…”

“…Standard perturbative approaches [119,122,166] As described in the previous section, the total Hamiltonian to be handled describes the electronic orbitals and the vibrations together with their Jahn-Teller interaction. Beyond this point, the problem resides in the way vibronic functions are found leading to energy levels and transition probabilities.…”

Calculation of the Jahn‐Teller Coupling Forces for ZnS:Cu2+ and GaP:Ni+

“…Using this formula and the fact that k > 0. 5 Including the effects of covalency and 2E-2T2 mixing, they found an S factor of 3 and a Jahn-Teller coupling frequency of ho = 300 cm-l indicating a moderately strong Jahn-Teller coupling. Within the same framework S = 2 and hwJT = 350 em-1 was found for GaP:Ni+ 131.…”

The Dynamic Jahn‐Teller Effect of Cubic ZnS:Cu2+‐ Attempt of Coupling to T2 Modes

“…

In a foregoing paper (1) two of the authors discussed in detail the interpretation centres in cubic ZnS. The complicated emis-2+ of the optical vibronic spectra of Cu sion spectrum with many narrow lines can be understood in t e r m s of a dynamic Jahn- The introduction of an additional coupling to T 2 vibrational modes of comparable centre in CaO (4).

+ strength seems to be crucial as experimentally verified for the F This is a very elaborate computational problem.

…”

“…The Dynamic Jahn-Teller Effect of Cubic ZnS:Cu2+-Attempt of Coupling to T 2 Modes BY 1) U. SAUER, U. SCHERZ, and H. MAIER In a foregoing paper (1) two of the authors discussed in detail the interpretation centres in cubic ZnS. The complicated emis-2+ of the optical vibronic spectra of Cu sion spectrum with many narrow lines can be understood in t e r m s of a dynamic Jahn- The introduction of an additional coupling to T 2 vibrational modes of comparable centre in CaO (4).…”