Differences in NEXAFS of odd/even long chain n-alkane crystals

We present the near edge X-ray absorption fine structure (NEXAFS) spectra of several long chain n-alkanes crystallites formed on Silicon nitride (Si3N4) windows. Dichroic signature was investigated with the CC backbone aligned perpendicular to the substrate. Significant changes in the dichroic signature of spectral intensities at energies below the ionization edge (287.5 and 288.1 eV) have been observed. While the dichroic ratio corresponding to the spectral feature at 287.5 eV remains relatively unaffected by the overall length of CC backbone, it is noticeably affected by the parity (odd or even) of the number of Carbon atoms in the n-alkane backbone. Data obtained provide evidence of the influence of interaction of molecular orbitals with periodic lattice structure.