A New Technique For Measuring Microscopic Temperatures
Imagine measuring the temperature of a single bacterium. Now consider the size of your average thermometer and the microscopic size of that bacterium. Sounds like an impossible task, right? But scientists have found a way - their method accurately measures the surface temperature of nanoscale objects, which are typically thousands of times smaller than the width of a single strand of hair. The only catch is that their temperature must be different than that of their environment.
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The research determined that temperatures of nanoscale objects can be measured by analyzing their random motion in air, called Brownian motion. "This motion is caused by the collisions with the air molecules," said Dr. Janet Anders, a quantum information theorist at the University of Exeter, in a press release. "We found that the impact of such collisions carries information about the object's surface temperature, and have used our observation of its Brownian motion to identify this information and infer the temperature."
The scientists conducted their research by trapping a glass nanosphere in a laser beam and suspending it in air. The sphere was then heated, making it possible to observe rising temperatures at the nanoscale until the glass got so hot that it melted. The technique could even measure various temperature changes across the surface of the sphere.
"When working with objects on the nanoscale, collisions with air molecules make a big difference," Dr. James Millen, of the University College London, said in the release. "By measuring how energy is transferred between nanoparticles, and the air around them, we learn a lot about both".
Temperature is critical for many nanotechnological devices used in the field of medicine, electronics, and biotechnology, among other industries. A slight variation in temperature can make or break an entire experiment when nanoparticles are involved. This new discovery will also help with future research attempting to bring large objects into a quantum superposition state, which is when a particle exists in all of its quantum states simultaneously. The research will also be useful in studies on the transportation of aerosols through the atmosphere.
Brownian motion is named after the Scottish botanist, Robert Brown, who first observed it in 1827. While looking at pollen in water under a microscope, he noticed that the particles were moving through water but he couldn't determine the mechanism that caused this motion. Many years later, in 1905, Albert Einstein published a paper describing the Brownian motion as a result of the pollen being moved by individual molecules of water, thus confirming the presence of atoms and molecules.
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