Decay Kinetics of Photoinduced Solitons on a One-Dimensional Lattice with Traps

摘要

The survival probability of solitons diffusing on a one-dimensional lattice with traps is studied numerically. Solitons are assumed to collapse once they collide with one another or reach traps. It turns out that, as the density of traps increases, the decay profile tends to change into an exponential-like form from an extremely nonexponential one specific to the geminate recombination on a trap-free lattice. The randomness of the distance between adjacent traps, as well as the disorder of the intersite energy barriers for the hopping motion of solitons, functions to reduce the deviation of the decay profile from that in the case of the trap-free lattice. Our calculation well reproduces the temperature-dependent decay profiles of the photoinduced neutral solitons that have been observed recently in the MX-chain compound { [Pt(en)_2][Pt(en)_2Cl_2]}_3(CuCl_4)_4.12H_20. It is suggested that traps are located at every 7 to 8 segments of the lattice and that the height of energy barriers is irregular to some extent. The periodicity of the valence of Cu ions is discussed on the basis of this result.