Airy Trap for Corrosive Compounds

How do you study a liquid so corrosive it will eat through almost any container? Try floating it on a cushion of gas. By doing just that, scientists have found clues to the molecular structure of liquid boron, a key to explaining some of its unique properties, like its electron deficiency and its ability to act as both an insulator and a metal, according to a report in the current Physical Review Letters. The technique may allow researchers to probe a host of other hard-to-handle substances.

Liquid boron is dangerous stuff--it runs at least 2100 degrees Celsius and is corrosive enough to dissolve virtually all containers. But a team led by Shankar Krishnan, a materials scientist at Containerless Research Inc. in Evanston, Illinois, found that a continuous jet of argon gas could suspend a boron crystal 3 to 4 millimeters wide in midair. The researchers then melted the solid with a laser beam and studied it using x-ray diffraction.

The team found that small clusters of boron molecules tend to form similar arrays in the liquid and solid states, not unlike the resemblance between H20 molecules in water and ice. But the researchers couldn't tell whether larger scale structures of boron molecules, like the trademark icosahedrons of boron crystals, exist in the liquid. It also remains unclear why boron, an insulator when solid, expands and becomes metallic after melting.

"The technique is intriguing," says Bill Glaunsinger, a chemist at Arizona State University in Tempe. "From an experimental point of view, it's a very significant contribution." Glaunsinger hopes the levitation technique can be used to shed light on other molecules with extreme properties.

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