Ultrafast photoluminescence dynamics in a quasi-one-dimensional halogen-bridged mixed-valence complex [Pt(en)₂][Pt(en)₂Cl₂](ClO₄) ₄

Ultrafast dynamics of luminescence from the unrelaxed self-trapped excitons in a quasi-one-dimensional halogen-bridged mixed-valence complex [Pt(en)₂][Pt(en)₂Cl₂](ClO₄) ₄ (en = ethylenediamine) has been investigated for the first time by femtosecond up-conversion method. The photoluminescence lifetime increases from 270 fs to 1.2 ps with wavelength from 570 nm to 660 nm. At longer wavelengths than 660 nm a component with a much longer lifetime than 10 ps was also observed.