Universal Signature of Hydrogen Bonding in the Oxygen K-Edge Spectrum of Alcohols

We present a study of the local electronic structure surrounding the OH group in a series of alcohols by X-ray Raman scattering at the oxygen K edge. The samples include the linear alcohols from methanol to butanol as well as the isomers isopropanol, isobutanol, and 2-butanol. For interpretation and computational benchmarks, we combine classical molecular dynamics (MD) simulations and density functional theory (DFT) spectrum calculations. The results indicate that intramolecular structure influences the spectra considerably. Nevertheless, hydrogen bonding produces a clear spectral signature that is nearly identical in all of the alcohols. The spectral calculations using MD structures closely reproduce the experimental results and support the picture provided by the MD simulations.