Carbon K-edge x-ray absorption spectra of liquid alcohols from quantum chemical calculations of liquid structures obtained by molecular dynamics simulations.

Abstract

For reproducing the carbon K-edge x-ray absorption spectra of liquid alcohols, inner-shell quantum chemical calculations based on the Hartree-Fock method were performed with the snapshots of the liquid structures obtained by molecular dynamics simulations. The C K-edge inner-shell spectrum of liquid ethanol (EtOH) was obtained by the summation of one thousand calculated spectra of EtOH molecules including neighbor EtOH molecules within the CH2-CH2 distance of 6 Å. For the C K-edge inner-shell spectrum of liquid methanol (MeOH), we have calculated one thousand spectra of MeOH molecules including neighbor MeOH molecules within the CH3-CH3 distance of 6 Å. The calculated C K-edge inner-shell spectra of liquid alcohols well reproduced the spectral shapes of the experimentally obtained x-ray absorption spectra and the spectral changes from gas to liquid phases.