Journal : Journal of Chemical Physics , vol. 142 , 2015
Publisher : AIP Publishing (American Institute of Physics)
International Standard Numbers
Printed : 0021-9606
Electronic : 1089-7690
Publication type : Academic article
Issue : 4
If you have questions about the publication, you may contact Nofima’s Chief Librarian.
The structure of bulk liquid water was recently probed by x-ray scattering below the temperature limit of homogeneous nucleation (TH ) of ∼232 K [J. A. Sellberg et al., Nature 510, 381-384 (2014)]. Here, we utilize a similar approach to study the structure of bulk liquid water below TH using oxygen K-edge x-ray emission spectroscopy (XES). Based on previous XES experiments [T. Tokushima et al., Chem. Phys. Lett. 460, 387-400 (2008)] at higher temperatures, we expected the ratio of the 1b1′ and 1b1″ peaks associated with the lone-pair orbital in water to change strongly upon deep supercooling as the coordination of the hydrogen (H-) bonds becomes tetrahedral. In contrast, we observed only minor changes in the lone-pair spectral region, challenging an interpretation in terms of two interconverting species. A number of alternative hypotheses to explain the results are put forward and discussed. Although the spectra can be explained by various contributions from these hypotheses, we here emphasize the interpretation that the line shape of each component changes dramatically when approaching lower temperatures, where, in particular, the peak assigned to the proposed disordered component would become more symmetrical as vibrational interference becomes more important.