ULTRAFAST SELF-TRAPPING DYNAMICS OF EXCITONS IN QUASI-ONE-DIMENSIONALHALOGEN-BRIDGED PLATINUM COMPLEX

We present the rot experimental results of femtosecond time-resolved l uminescence measurements of a self-trapped exciton (STE) luminescence band in quasi-one-dimensional halogen-bridged platinum complex [Pt(en) (2)][Pt(en)(2)Cl-2](ClO4)(4). The time evolution of luminescence has b een investigated at room temperature using up-conversion technique. In high-energy tail of the band (from 1.8 to 2.1 eV), a very fast rise a nd decay are seen. while a slow rise of about 450 fs is observed aroun d the luminescence peak energy. This rise becomes faster at the low en ergy side of the band. These behaviors are explained by the cooling of STE's just after the rapid self-trapping of photo-generated charge-tr ansfer excitons. (C) 1998 Elsevier Science B.V. All rights reserved.