A group of researchers headed by the Department of Energy’s Oak Ridge National Laboratory has discovered an innovative method to find out the local temperature of a material from an area with a width of just one-billionth of 1 m, or roughly 100,000 times thinner than a strand of human hair.

This finding has been reported in the Physical Review Letters journal, and it assures to enhance knowledge of practical but atypical chemical and physical properties that appear in structures and materials at the nanoscale. The potential to find out nanoscale temperatures can assist in revolutionizing semiconducting materials, microelectronic devices, and other technologies, whose advancement is reliant on delineating the atomic-scale vibrations that occur due to heat.

The researchers adopted a method known as electron energy gain spectroscopy in a newly procured, specialized instrument that generates images by using both great spectral and high spatial resolution detail. The instrument, with a height of 13 feet and fabricated by Nion Co., is known as HERMES, an acronym for High Energy Resolution Monochromated Electron energy-loss spectroscopy-Scanning transmission electron microscope.

It is a known fact that atoms are always dynamic. An increase in temperature increases their dynamics. In this study, the researchers adopted the new HERMES instrument to evaluate the temperature of semiconducting hexagonal boron nitride through direct observation of the atomic vibrations corresponding to heat inside the material. Collaborators from Nion, the developer of HERMES, and Protochips, the developer of a heating chip used in the experiment, also took part in the study.

“What is most important about this ‘thermometer’ that we have developed is that temperature calibration is not needed,” stated physicist Juan Carlos Idrobo from the Center for Nanophase Materials Sciences, a DOE Office of Science User Facility at ORNL.

Image Credit:  Oak Ridge National Laboratory, U.S. Dept. of Energy; photographer Jason Richards

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