New method for measuring the temperature of nanoscale objects discovered

Temperature measurements in our daily life are typically performed by bringing a thermometer into contact with the object to be measured. However, measuring the temperature of nanoscale objects is a much more tricky task due to their size – up to a thousand times smaller than the width of a human hair.

Pioneering new research, published in Nature Nanotechnology, has developed a method to measure the temperature of nanoscale objects when it is different to that of their environment. A team led by Dr. Janet Anders at the University of Exeter and Professor Peter Barker at University College London have discovered that the surface temperature of nanoscale objects can be determined by analysing their jittery movement in air - known as Brownian motion. This motion is caused by the collisions with the air molecules and was first explained by Einstein in one of his famous 1905 papers.

“When working with objects on the nanoscale, collisions with air molecules make a big difference”, says Dr. James Millen from the team at University College London, “by measuring how energy is transferred between nanoparticles and the air around them we learn a lot about both”.

The scientists conducted their research by trapping a glass nanosphere with a laser and suspending it in air. The sphere was then heated, and it was possible to observe rising temperatures on the nanoscale, even to the point at which the glass boiled.  This technique could even discern different temperatures across the surface of the tiny sphere.

Accurate knowledge of temperature is essential for the operation of many nanotechnological devices. The discovery informs current research on bringing large objects into a quantum superposition state. It also impacts on the study of aerosols in the atmosphere, and opens the door for the study and understanding of process that are not in equilibrium.

Related links:

• Journal link: Nature Nanotechnology (front cover of June 2014 edition)
• IEEE Spectrum blog post: IEEE