Random-walk annihilation process of photo-induced neutral-ionic domain walls in TTF-CA
1. Physikalisches Institut, Universität Stuttgart - Pfaffenwaldring 57, 70550 Stuttgart, Germany
Received: 21 October 2014
Accepted: 9 March 2015
The charge and lattice dynamics at the neutral-ionic phase transition in the organic mixed-stack compound TTF-CA were measured by time-resolved Fourier-transform infrared spectroscopy and modeled by Monte Carlo simulations on a one-dimensional chain. After photoexcitation in the ionic state, we observe transient changes in reflectivity, which follow a stretched-exponential behavior on a microsecond time scale. This implies that the dimerization between the TTF and CA molecules vanishes, creating metastable domains. The time, temperature and intensity dependences can be modeled by a diffusion-annihilation process of neutral-ionic domain walls. Their random walk explains the relaxation process and its characteristic decay with time.
PACS: 78.30.Jw – Organic compounds, polymers / 78.47.D- – Time resolved spectroscopy (>1 psec) / 64.60.My – Metastable phases
© EPLA, 2015