COLUMBUS, Ohio -- A study at Ohio State University is probing the nature
of a unique sulfur-containing molecule -- one that scientists consider a
"missing link" in its chemical family.
This model depicts hydrogen thioperoxide, or HSOH, a
molecule thought to be a "missing link" in its chemical family. Here
gray represents hydrogen atoms, yellow a sulfur atom, and red an
oxygen atom. Ohio State University physicists and their colleagues
in Germany were the first to synthesize the molecule in the
laboratory, and record its unique spectrum. Graphic courtesy of Ohio
State University.
The molecule, hydrogen thioperoxide, or HSOH for short, is related to
the common bleaching and disinfectant agent hydrogen peroxide. Because
HSOH contains sulfur, it could eventually help scientists understand how
pollutants form in Earth's atmosphere, and how similar molecules form in
outer space.
Scientists presented an initial study of the molecule June 18, 2002, at
the annual International
Symposium on Molecular Spectroscopy at Ohio State University.
A special laboratory instrument is allowing physicists here to study
the molecule in detail for the first time. Frank
De Lucia, professor of physics
at Ohio State, and his colleagues designed the instrument to utilize
their FAST
Scan Submillimeter Spectroscopy
Technique (FASSST).
The technique offers a quick way for scientists to examine the spectrum
of light given off by a molecule. Each molecule has its own one-of-a-kind
spectral pattern. FASSST takes a snapshot of a wide range of spectral
wavelengths, so scientists can easily recognize the pattern of the
molecule they are looking for.
Since the 1960's, scientists have speculated that a sulfur molecule
like HSOH could exist in Earth's upper atmosphere and outer space. Coal
burning power plants, for instance, release sulfur from smokestack
exhaust, and HSOH's other main ingredient -- water -- is abundant in the
atmosphere.
But no one was able to synthesize the HSOH in the laboratory until
Markus Behnke, a graduate student at the University of Cologne, Germany,
did so in 2001. His collaborators on the HSOH synthesis project included
Josef Hahn, Gisbert Winnewisser, and Sven Thorwirth at the University of
Cologne, and Jürgen Gauss at Johannes Gutenberg University in Mainz,
Germany.
Behnke, now a postdoctoral researcher at Ohio State, explained that
HSOH is considered a "missing link" molecule. With its mixture of
hydrogen, oxygen, and sulfur, it exists somewhere between simple,
sulfur-free molecules such as hydrogen peroxide and more complex molecules
like sulfuric acid.
In his symposium presentation this week, Behnke reported the first
detailed spectroscopic identification of HSOH using FASSST.
The molecule was very difficult to study, because it exists only in
extreme conditions: it is created during combustion at very high
temperatures, but it breaks down unless it can be transferred quickly to
an environment with very low temperature and pressure, such as the upper
atmosphere. In addition, the chemical reaction that creates HSOH creates
many other similar molecules at the same time.
Given those circumstances, synthesizing HSOH and recording its spectrum
in the laboratory wasn't so much like looking for a needle in a haystack
as "looking for an ant somewhere in Canada," Behnke said.
The Ohio State physicists were able to create the molecule in a
high-temperature chemical reaction -- approximately 1100°C (2000°F), and
used FASSST to image the spectrum.
Scientists could one day use information about HSOH to better
understand combustion, atmospheric pollution, and interstellar
chemistry.
"This is very fundamental research," Behnke said, "but knowing the
structure of simple molecules like HSOH could give us the foundation to
understand more complex molecules later."
The National Science Foundation funded this
work.
Contact: Markus Behnke, (614) 292-1971; Behnke.14@osu.edu
Frank De Lucia,
(614) 688-4774; Delucia.2@osu.edu
Written by Pam Frost Gorder Gorder.1@osu.edu
