AVS 47th International Symposium
    Biomaterial Interfaces Wednesday Sessions
       Session BI+SS-WeM

Paper BI+SS-WeM4
Hydrogen Bond of Water in Ih Ice Probed by Core-level Spectroscopies

Wednesday, October 4, 2000, 9:20 am, Room 202

Session: Water at Biointerfaces
Presenter: H. Ogasawara, Uppsala University, Sweden
Authors: H. Ogasawara, Uppsala University, Sweden
D. Nordlund, Uppsala University, Sweden
M. Cavalleri, Uppsala University, Sweden
L.-A. Näslund, Uppsala University, Sweden
M. Nagasono, Uppsala University, Sweden
L.G.M. Petterson, Uppsala University, Sweden
A. Nilsson, Uppsala University, Sweden
Correspondent: Click to Email
In biological complexes, DNA, protein and so on, materials consist of two types of chemical bonds. A shorter covalent bond has the strength of a few eV to construct molecular flame, and longer hydrogen bond has the strength of a few tenth meV. This energetically weak nature of hydrogen bond gives flexibility and enables the self-organization of molecules at ambient temperature. Ice is a unique material that hydrogen and oxygen atoms in the crystal are connected both covalent and hydrogen bonds where each oxygen atom has two covalent O-H bonds and two hydrogen O-H bonds. Here we report electronic structure of water in Ih ice, a thin film grown on Pt(111), studied with combination of core-level spectroscopies, X-ray absorption spectrosocpy (XAS), X-ray emission spectroscopy (XES) and theoretical simulation (DFT calculation). The experiments were performed at MAX-LAB, Sweden. The details of the endstation is described elsewhere.@footnote 1@ The theoretical simulation of spectra was done using the deMon program@footnote 2@ XAS and XES results indicate a reconfigration of molecular orbitals of water in ice beside the binding energy shift. In O 1s XAS, 4a@sub 1@ resonance is severely suppressed indicating the enhancement of s-character of this orbital compared to that of the gas phase. In O 1s XES, 3a@sub 1@ emission is suppressed showing the strong s-character of this orbital. From these observations we conclude that a water molecule in ice has a pseudo-totally-symmetric character. This pseudo-totally-symmetric character of water in ice is confirmed by excitation profile of 3a@sub 1@ photoemission peak and theoretical simulation. @FootnoteText@ @footnote 1@ R. Denechke et al, J. Electron Spectrosc. Relat. Phenom. 101-103, 971(1999). @footnote 2@ deMon-KS version 4.0, deMon Software, (1997).