Spectroscopic probing of local hydrogen-bonding structures in liquid water

• Published in: Journal of physics. Condensed matter 2002-03, Vol.14 (8), p.L213-L219
• Main Authors: Myneni, S, Luo, Y, Näslund, L Å, Cavalleri, M, Ojamäe, L, Ogasawara, H, Pelmenschikov, A, Wernet, Ph, Väterlein, P, Heske, C, Hussain, Z, Pettersson, L G M, Nilsson, A
• Format: Article
• Language: English
• Subjects: ammonia; Chemistry; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; d2o; desorption; dynamics; edge; Electron states; Electronic structure of liquid metals and semiconductors and their alloys; Exact sciences and technology; Fysikalisk kemi; h2o; hydrogen bonding; k-shell excitation; Kemi; molecules; NATURAL SCIENCES; NATURVETENSKAP; photoion; Physical chemistry; Physics; region; Structure of liquids; Structure of simple liquids; Structure of solids and liquids; crystallography; water
• ISSN: 0953-8984; 1361-648X; 1361-648X
• DOI: 10.1088/0953-8984/14/8/106

We have studied the electronic structure of liquid water using x-ray absorption spectroscopy at the oxygen K edge. Since the x-ray absorption process takes less than a femtosecond, it allows probing of the molecular orbital structure of frozen, local geometries of water molecules at a timescale that has not previously been accessible. Our results indicate that the electronic structure of liquid water is significantly different from that of the solid and gaseous forms, resulting in a pronounced pre-edge feature below the main absorption edge in the spectrum. Theoretical calculations of these spectra suggest that this feature originates from specific configurations of water, for which the H-bond is broken on the H-donating site of the water molecule. This study provides a fingerprint for identifying broken donating H-bonds in the liquid and shows that an unsaturated H-bonding environment exists for a dominating fraction of the water molecules.