Their work paves the way for a better understanding of the role played by tiny airborne salt particles, emitted into the air by crashing waves and sea spray, in a slew of atmospheric and environmental processes, such as the destruction of the ozone layer.
"This is important because many atmospheric phenomena are driven by reactions with the surface of sea salt aerosols," says Miquel Salmeron, a physicist with Berkeley Lab's Materials Sciences Division who has pioneered new ways of exploring the molecular behavior of liquids on surfaces. "We found that anions [negatively charged ions] concentrate at the surface of salt grains as they dissolve in water."
The research also underscores the merits of a new spectroscopy system, recently developed by Salmeron and colleagues, which enables scientists to study the chemical underpinnings of everyday catalytic, biological, and ecological phenomena in their natural environment, that is, at almost normal pressures and in the presence of water vapor.
Their study was published in the Jan. 28 issue of the journal Science.
The ALS is one of only two places in the world where photoelectron spectroscopy can be performed on surfaces at pressures above 1 torr (a unit of pressure equivalent to 1 millimeter of mercury in a barometer). The only other such instrument is at a synchrotron in Berlin, Germany, which follows Salmeron's design. All other photoelectron spectroscopy systems require a dry, high-vacuum environment.
"But a lot of information is lost once a compound is placed in a vacuum, so we developed an instrument to circumvent this problem. In
Contact: Dan Krotz
DOE/Lawrence Berkeley National Laboratory