Film-thickness dependent optical properties of durham trans-polyacetylene

Summary form only given. We present results of optical measurements in the infrared (IR) and ultraviolet/visible region (UV/Vis) obtained on Durham trans-polyacetylene (PA) with varying thickness. We find a scaling of IR-modes, of the low energy peak of the photoinduced absorption (PIA) and the UV/Vis absorption and reflection spectra with the optical density (OD) of the samples. For PA of a chainlength of /spl ap/ 1600 CH-units the strongest dependence is observed within a thickness range of 6 - 200nm. The effective conjugation length (/spl iota//sub c,eff/) increases with decreasing thickness. This interpretation is supported by theoretical calculations to simulate the possible effects of varying concentration of absorbers and varying thickness in a material of unchanged dielectric function.