Selective photon-breaking of C-S bonds in polythiophene to form quasi-one-dimensional carbon chains in cubic nanocrystals

Abstract

A solid polythiophene pellet was ablated by a KrF excimer laser beam to deposit thin films on silicon substrates. The laser-ablated plasma was studied by optical emission spectroscopy to identify the photon-breaking of C-S bonds in the ablated heterocycles. The selective photon-induced bond breaking was also supported by Raman and X-ray photoelectron spectroscopy measurements of the deposited thin films. The thin films appeared to be composed of cubic nanocrystals with an uniform size of 240 nm. X-ray diffraction measurement determined the cubic crystal structures with a lattice constant of a = 3.38 Å and suggested a quasi-one-dimensional carbon chain structure along the body diagonal of the cube.