Analysis of spectra of neat and lanthanide ion-doped KPb <inf>2</inf>Cl <inf>5</inf> excited by synchrotron radiation

Abstract

The excitation and emission spectra of neat K 2PbCl 5, and also doped with the lanthanide ions Pr 3+, Nd 3+, Er 3+ and Tm 3+ have been recorded at temperatures down to 10K using synchrotron radiation. To facilitate the spectral assignments, a first principles calculation has been performed and despite its inaccuracies it confirms the nature of the lower energy levels of this system. The lowest energy transitions in the excitation spectrum are Pb 2+-centred, whereas the band gap transitions, which are essentially of a charge transfer (CT) nature, are at shorter wavelengths. The emission transitions are likewise assigned to those from the Pb 2+ 3P 1,0 states, and from the band gap. The Stokes shift of the latter transition is ~18000cm -1. Under synchrotron radiation excitation, the energy transfer from the host or Pb 2+ levels to 4f N lanthanide ion levels is not efficient. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.