As units proceed to shrink, new challenges of their measurement and design current themselves. For units primarily based on molecular junctions, by which single molecules are sure to metals or semiconductors, we now have quite a lot of methods to check and characterize their electrical transport properties. In distinction, probing the thermal transport properties of such junctions on the nanoscale has confirmed tougher, and lots of temperature-related quantum phenomena in them stay poorly understood.
In a couple of research, scientists managed to measure the thermal transport properties in molecular junctions on the nanoscale utilizing a method referred to as scanning thermal microscopy (SThM). This methodology entails placing a really sharp metallic tip involved with the goal materials and shifting this tip all through the fabric’s floor. The tip, which is heated from behind utilizing a laser, incorporates a thermocouple. This small gadget measures temperature variations, and so by balancing the heating of the tip attributable to the laser with the tip’s cooling attributable to warmth flowing into the goal pattern, it turns into doable to measure a fabric’s thermal transport traits level by level.
In a current examine revealed in Journal of the American Chemical Society, scientists from Tokyo Tech reported a serendipitous but vital discovering whereas utilizing SThM. The group was using a SThM method to measure the thermal transport properties of self-assembled monolayers (SAMs). These samples contained alternating stripes of every of the three doable pairs amongst n-Hexadecanethiol, n-Butanethiol, and Benzenethiol. Besides using the usual contact-based SThM method, the researchers tried utilizing a non-contact regime as properly, by which the tip of the scanning thermal microscope was stored above the pattern with out touching it. Unexpectedly, they realized this non-contact regime had some severe potential.
In the contact SThM regime, warmth flows immediately from the tip to the pattern. By distinction, within the non-contact SThM regime, the one warmth switch between the tip and the pattern happens by way of heat radiation. As the group realized via experiments, whereas the contact regime is finest for visualizing the thermal transport traits, the non-contact regime is far more delicate to the precise size of the molecules “sticking out” from the substrate. Thus, the mix of the non-contact and phone regimes gives an all-new means of making topographic and thermal transport photographs of a pattern concurrently.
Moreover, the non-contact method has benefits over different well-established microscopy methods, as Associate Professor Shintaro Fujii, lead creator of the paper, explains: “The non-contact SThM approach is completely non-destructive, unlike other techniques like atomic force microscopy, which does require contact between the scanning tip and the sample and thus has a mechanical impact that can damage soft organic materials.”
Overall, the perception supplied by this examine will pave the way in which to novel technological advances and a deeper comprehension of supplies on the nanoscale. “Our work not only is the first to provide thermal images of organic SAMs, but also provides a new technique for investigating thermal transport properties, which will be essential for thermal management in various types of nanodevices,” concludes Fujii.
Let us hope this work helps scientists elucidate the numerous mysteries of thermal phenomena.
Shintaro Fujii et al, Visualization of Thermal Transport Properties of Self-Assembled Monolayers on Au(111) by Contact and Noncontact Scanning Thermal Microscopy, Journal of the American Chemical Society (2021). DOI: 10.1021/jacs.1c09757
Tokyo Institute of Technology
Visualizing temperature transport: An surprising method for nanoscale characterization (2021, November 17)
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