High-resolution soft X-ray photoelectron spectra of liquid water (H 2O and D2O) were measured using a liquid beam photoelectron spectrometer. The 1a1 (O1s) band and the lowest valence 1b1 band had single peaks, which is not consistent with the split 1b1 → 1a1 of the X-ray emission band of liquid water if the splitting is assumed to originate from level shifts in two different hydrogen bonding structures. The second valence 3a1 band of liquid water exhibited a flat top implying that two bands exist underneath a broad feature, which is similar to the case of the 3a1 band of amorphous ice. The energy splitting between the two 3a1 bands is estimated to be 1.38 eV (H2O) and 1.39 eV (D2O). Ab initio calculations suggest that the large splitting of the 3a1 band is characteristic of water molecules that function as both proton donor and acceptor. The overall result is consistent with the conventional model of a tetrahedral hydrogen-bonding network in liquid water.
All Science Journal Classification (ASJC) codes
- Physics and Astronomy(all)
- Physical and Theoretical Chemistry