Temperature inside collapsing bubble four times that of sun

Mar 02, 2005

Using a technique employed by astronomers to determine stellar surface temperatures, chemists at the University of Illinois at Urbana-Champaign have measured the temperature inside a single, acoustically driven collapsing bubble.
Their results seem out of this world.

"When bubbles in a liquid get compressed, the insides get hot -- very hot," said Ken Suslick, the Marvin T. Schmidt Professor of Chemistry at Illinois and a researcher at the Beckman Institute for Advanced Science and Technology. "Nobody has been able to measure the temperature inside a single collapsing bubble before. The temperature we measured -- about 20,000 degrees Kelvin -- is four times hotter than the surface of our sun."

This result, reported in the March 3 issue of the journal Nature by Suslick and graduate student David Flannigan, already has raised eyebrows. Their work is funded by the National Science Foundation and the Defense Advanced Research Projects Agency.

Sonoluminescence arises from acoustic cavitation -- the formation, growth and implosion of small gas bubbles in a liquid blasted with sound waves above 18,000 cycles per second. The collapse of these bubbles generates intense local heating. By looking at the spectra of light emitted from these hot spots, scientists can determine the temperature in the same manner that astronomers measure the temperatures of stars.

By substituting concentrated sulfuric acid for the water used in previous measurements, Suslick and Flannigan boosted the brilliance of the spectra nearly 3,000 times. The bubble can be seen glowing even in a brightly lit room. This allowed the researchers to measure the otherwise faint emission from a single bubble.

"It is not surprising that the temperature within a single bubble exceeds that found within a bubble trapped in a cloud," Suslick said. "In a cloud, the bubbles interact, so the collapse isn't as efficient as in an isolated bubble."

What is surprising, however, is the extremely high temperature the scientists measured. "At 20,000 degrees Kelvin, this emission originates from the plasma formed by collisions of atoms and molecules with high-energy particles," Suslick said. "And, just as you can't see inside a star, we're only seeing emission from the surface of the optically opaque plasma." Plasmas are the ionized gases formed only at truly high energies.

The core of the collapsing bubble must be even hotter than the surface. In fact, the extreme conditions present during single-bubble compression have been predicted by others to produce neutrons from inertial confinement fusion.

"We used to talk about the bubble forming a hot spot in an otherwise cold liquid," Suslick said. "What we know now is that inside the bubble there is an even hotter spot, and outside of that core we are seeing emission from a plasma."

Source: University of Illinois at Urbana-Champaign

Explore further: Two Galileo satellites lose their way

add to favorites email to friend print save as pdf

Related Stories

A new process for making much-sought iron nanospheres

Feb 19, 2007

Using a process that creates bubbles as hot as the surface of the sun, chemists are reporting development of a new method for making hollow hematite (iron oxide) nanospheres. The University of Illinois at Urbana-Champaign's ...

Recommended for you

Two Galileo satellites lose their way

1 hour ago

Two European Galileo satellites launched as part of a navigation system designed to rival GPS have failed to locate their intended orbit, launch firm Arianespace said Saturday.

SpaceX rocket explodes during test flight

10 hours ago

A SpaceX rocket exploded in midair during a test flight, though no one was injured, as the company seeks to develop a spacecraft that can return to Earth and be used again.

Amazing raw Cassini images from this week

Aug 22, 2014

When Saturn is at its closest to Earth, it's three-quarters of a billion miles away—or more than a billion kilometers! That makes these raw images from the ringed planet all the more remarkable.

Europe launches two navigation satellites

Aug 22, 2014

Two satellites for Europe's rival to GPS were lifted into space on Friday to boost the Galileo constellation to six orbiters of a final 30, the European Space Agency (ESA) said.

SpaceX gets 10-year tax exemption for Texas site

Aug 22, 2014

Cameron County commissioners have agreed to waive 10 years of county taxes as part of an agreement bringing the world's first commercial site for orbital rocket launches to the southernmost tip of Texas.

User comments : 0