There's a new, first-of-its-kind ion microprobe in the Laboratory for Space Sciences in Arts & Sciences. And the researchers there are so proud of the $2 million instrument -- which measures the isotopes of interstellar grains at a size range (less than or equal to 500 atoms) never seen before -- that they want to show it and the resulting research off to the University community.

They also want to bring the instrument's capabilities to the attention of other researchers, including those in fields such as chemistry, biology and biomedical sciences.

It's the NanoSIMS, short for Secondary Ion Mass Spectrometer, and it's the first instrument in the world built to analyze the isotopic and elemental composition of extremely small samples, such as interplanetary dust particles and meteorite grains, at a sub-micrometer scale, allowing a first-time look at those particles' subcomponents.

Members of the University community are invited to see the NanoSIMS at work during an open house April 2. The event begins with remarks at 3:30 p.m. in Crow Hall, Room 201, followed by guided tours of the NanoSIMS laboratory on the fourth floor of Compton Hall. Computer monitors in the lab will display images of interplanetary dust particles measured with the new instrument.

"While a typical ion microprobe can measure interstellar material weighing as little as a millionth of a millionth of a gram, the NanoSIMS allows us to measure particles with 1,000 times less mass," said Frank J. Stadermann, Ph.D., senior research scientist in physics and director of the NanoSIMS lab.

The NanoSIMS extends the study of such grains from a micrometer in size -- not visible to the naked eye -- to grains with a thousand times less volume, which is more characteristic of interstellar dust.

By studying the isotopic composition of these particles, space science researchers are gaining new information on the nuclear and chemical processes in stars and on conditions during the solar system's formation.

The Laboratory for Space Sciences is part of the departments of Physics and Earth and Planetary Sciences and the McDonnell Center for the Space Sciences, all in Arts & Sciences.

Making remarks at the open house will be Robert M. Walker, Ph.D., the McDonnell Professor of physics, former director of the McDonnell Center and an early supporter of the NanoSIMS' construction; Roger Phillips, Ph.D., the center's current director and professor of earth and planetary sciences; and Stadermann.

"It was rather risky to invest so much money in an instrument that was the first of its kind," Stadermann said. "We didn't know how everything would work out once it was actually in our lab and we were on our own.

"But once we performed extensive tests to verify it was indeed capable of performing all the measurements we always wanted to do, and it became fully operational, researchers in our lab were soon making scientific discoveries that would have been impossible with prior tech-nologies."

Stadermann noted that the instrument's success was obvious to researchers from around the world attending the 33rd Lunar and Planetary Science Conference held earlier this month in Houston. Eight of the 19 presentations from the Laboratory for Space Sciences at this conference -- one of the biggest annual scientific meetings in the field -- were based on measurements using the NanoSIMS.

The NanoSIMS combines high sensitivity with a small ion beam that bombards a sample. The beam's impact sputters the matter, triggering a cascade of atomic collisions. Atoms and atomic clusters are ejected and during the ejection process, some atoms and clusters are ionized.

The atoms are then collected by electrical fields and transmitted to a mass spectrometer that sorts them. Up to five ions of different mass originating from the sputtered volume can be simultaneously recorded and measured, ensuring perfect isotope registration.

"We are very open to new ideas for NanoSIMS' uses and new scientific collaborations," Stadermann said. "We have an open-door policy with regard to access to our equipment. There might be some practical applications in the biomedical field, such as using the instrument in isotope tracer imaging or looking at the subcellular structures of cancer cells. We are always interested in seeing what other kinds of interesting science can be done."

Compared with what it measures -- sub-micron particles -- the NanoSIMS is enormous, taking up almost the whole width of two standard lab bays.

The journey from the NanoSIMS' conception to installation in Compton Hall took more than 10 years. George Slodzian, a professor at the University of Paris, invented the NanoSIMS, and the first instrument benefited from input by researchers at Washington University and the Max-Planck Institut fŸr Chemie in Mainz, Germany.

Over a 5-year period, Walker; Ernst Zinner, Ph.D., director of the McDonnell Center's Ion Microprobe Laboratory; and Stadermann worked on Slod-zian's prototype instrument in Paris, testing the basic capabilities of the ion optics and other design features.

This group of researchers defined modifications that were then incorporated into the new instrument for superior elemental and isotopic measurements. The Max-Planck Institut received the second NanoSIMS last year.

Manufactured at the CAMECA factory in Paris, the Washington University NanoSIMS was packed into four huge wooden crates -- the largest one alone had a gross weight of almost 3 tons -- and then sent by air cargo to New York. It was then trucked to St. Louis in two semitrailers.

When it finally arrived two months later on Dec. 1, 2000, it took a week just to get the instrument up to the fourth floor of Compton.