Photoinduced Near-Infrared Absorption in an M–X Chain Complex [Pt(en)₂][Pt(en)₂Cl₂](ClO₄)₄, en=ethylenediamine

Abstract

The near-infrared absorption spectrum has been measured in [Pt(en)₂][Pt(en)₂Cl₂](ClO₄)₄, (en)=ethylenediamine, irradiated with the 488 nm beam of an Ar-ion laser. In addition to the well-established intragap bands A around 1.6 eV and B around 2.0 eV, a broad band B′ is found to overlap the B band and be spread beyond 2.3 eV. No bands can be found at photon energies down to 1.2 eV below the A band. The results are discussed in relation to the “two-band” theory for polarons and solitons by Tinka-Gammel and coworkers (Phys. Rev. B45 (1992) 6435).