“Sometimes a negative result can be very positive.” — PAVEL JUNG WIRTH
Water-air interface is barely there
Interactions at thin surface layer have no impact down below
Jungwirth of the Academy of Sciences of
the Czech Republic in Prague, who wrote
a commentary on the work in the same
issue of Nature.
“In some ways this is a negative
result,” Jungwirth says. “Sometimes a
negative result can be very positive.”
Insights into the behavior of water
molecules at this superthin layer may
give scientists a better understand-
ing of the bonding and behavior of
pollutants or other compounds inter-
mingling at the surface. The new data
might also improve models of water’s
interactions with the atmosphere and
within cells, says physical chemist
Dennis Hore of the University of Victo-
ria in British Columbia.
H2O below refutes an idea that’s been
bandied about for ages — that water molecules deeper down will fall into lock-step, organizing themselves into orderly
layers, says Jungwirth.
By Rachel Ehrenberg
Where sea meets sky, there are lots of
water molecules with an identity crisis.
About a quarter of the H2O in water’s
uppermost layer can’t decide whether
to be liquid or gas: One hydrogen atom
stays in the drink while the other pokes
up, vibrating in the air.
“After the first layer, it’s all over,” he
says. “A lot of people still subscribe to
this long-range idea. But this shows very
clearly that you don’t have long-range
order in water.”
This layer of molecular ambiguity is
extremely thin and has little or no effect
on the water below it, new data reported
June 9 in Nature show. Right beneath the
liquid’s surface, water molecules go about
their business as if the air weren’t there.
That may seem like a dull discovery,
but the find is important, says Pavel
The fact that water molecules with
one hydrogen waving in the air have little effect on the arrangement of all the
Despite covering roughly 70 percent
of Earth’s surface and constituting about
60 percent of the human body, water still
puzzles scientists. For example, accord-
ing to water’s structural properties, it
shouldn’t be liquid, but rather gas, at
everyday temperatures and pressures.
“Water may be the most common
substance on Earth. But from a physics
standpoint, it is pretty unusual,” says
study coauthor Alexander Benderskii of
the University of Southern California in
Los Angeles.
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