Photoluminescence, absorption, and Raman spectra of a polydiacetylene monolayer

Optical properties of a single layer of polydiacetylene [poly-(heptacosa-10,12-diynoic acid)] have been studied. The morphology of the sample does not affect the optical properties. However, the exciton peak energy depends on the monolayer orientation with respect to the substrate. We tentatively ascribe the effect to stress variation in the first layer on the substrate.