Fourier transform-infrared spectroscopy has been used to detect conformational defects in certain crystalline n-alkanes (20 less than or equal to n less than or equal to 50) and homologous mixtures. The results indicate the existence of gauche conformers (trans-gauche, double gauche and "king") in the low-temperature solid-state structures of the single n-alkanes (greater than or equal to n-C36H68) and homologous mixtures; implying the existence of end-chain bending and folding. The data have been rationalized in terms of a model which incorporates surface melting and near-neighbour inter-molecular interactions.