The findings appeared April 1 in Science magazine's advance publication web site. "The results overturn 20 years of research in the physical chemistry of water," says SLAC's Anders Nilsson, the team's leader. "It's going to be a big shock in the whole field," he says.
The SSRL is a division of the Stanford Linear Accelerator Center, a U.S. Department of Energy facility operated by Stanford University. The project was a collaboration between researchers at SSRL, Stockholm University, Linkping University (Sweden) and the University of Utrecht (Holland).
As its H2O formula suggests, each water molecule is made of two atoms of hydrogen and one of oxygen. In ice, water molecules are arranged in a crystal structure, with each molecule typically linked to four others through what chemists call hydrogen bonds. In a hydrogen bond, electrostatic forces stick together a hydrogen atom from one molecule with the oxygen atom from a different molecule. The oxygen can form two hydrogen bonds, so a molecule can link to up to four others with two links through its oxygen and one through each of its hydrogens.
Although they are ten times weaker than the "covalent" bonds within the molecule itself, hydrogen bonds between molecules still take a lot of energy to break up which is why ice melts so slowly. Even in liquid water, molecules spend most of their time clumped together by hydrogen bonds, though not in a static pattern as in ice. "Hyd
Contact: Neil Calder
DOE/Stanford Linear Accelerator Center