The effect of metal alternation (Pt and M) in linear-chain halogen-bridged mixed-valence complexes, [M(en)2][PtX2(en)2](CIO4)4, (X=C1, Br and I; M=Pt, Pd and Ni; en = ethylenediamine), has been investigated using polarized reflection measurements. The electronic absorption spectra of these materials, obtained by applying the Kramers-Kronig relation to the reflectivity data, show two distinctive charge-transfer exciton bands associated with the inter-metal transitions, “M-Pt”, and the transitions from halogen ions to metal ions, “X-Pt”. On substitution of M=Pt by Pd or Ni, the absorption intensity of the “X-Pt” exciton was enhanced in contrast to the reduction of the “M-Pt” exciton intensity. The intensity borrowing between these two excitons is consistent with a numerical calculation based on a trimer model of the CT exciton transitions.
- Charge transfer
- Halogen-bridged mixed-valence complexes
- Kramers-Kronig transformation
- Metal substitution
- Optical properties
ASJC Scopus subject areas
- Physics and Astronomy(all)