Abstract
The detailed behavior of the wave-packet motion on the adiabatic potential surface of a self-trapped exciton is investigated in the quasi-one-dimensional halogen-bridged platinum complex [Pt(en) 2 ][Pt(en) 2 Br 2 ](ClO 4 ) 4 by means of time resolved luminescence spectroscopy. We have achieved a time-resolution of about 40 fs and found the frequency of the luminescence intensity oscillation twice as high as that of the wave-packet oscillation. Furthermore we have confirmed the anti-phasing behavior between the luminescence oscillations on the opposite sides of the potential minimum. Analyzing these results, we have succeeded in tracing the center of gravity motion of the wave-packet on the femtosecond time scale.