Ultrafast optical response in a quasi-one-dimensional halogen-bridged mixed-valence complex [Pd(en)2] [PdCl2(en)2] (ClO4)4

Abstract

The ultrafast optical response in a quasi-one-dimensional halogen-bridged mixed-valence complex [Pd(en)2] [PdCl2(en)2] (ClO4)4 (en = ethylenediamine) has been investigated by the use of a femtosecond absorption spectrum, calculated from a pump—probe reflection spectrum at room temperature by the Kramers—Kronig relations. The time dependence of the transient photoinduced absorption around 1.7 eV and the bleaching from 1.9 to 2.5 eV were calculated for three decay components. They are free excitons with a lifetime of about 800 fs, self-trapped excitons with a lifetime of about 3 ps, and polaron pairs which relax within a 100 ps time period.