Thermal Transport Properties of Self-Assembled Monolayers


Gadgets have been shrinking by the day, and new difficulties of their measurement and design current themselves. The electrical transport properties of gadgets primarily based on molecular junctions, the place single molecules are certain to semiconductors or metals, may be analyzed and characterised utilizing completely different strategies.

Picture Credit score: Tokyo Institute of Know-how

Alternatively, investigating the thermal transport properties of such junctions on the nanoscale has been harder, and a number of other temperature-related quantum phenomena in them are usually not understood so nicely.

In some research, researchers managed to quantify the thermal transport properties in molecular junctions on the nanoscale with the assistance of a way often called scanning thermal microscopy (SThM). On this approach, a really sharp metallic tip is positioned involved with the goal materials and the tip is moved throughout the fabric’s floor.

The tip is heated from behind via a laser and consists of a thermocouple. This small gadget quantifies temperature variations and thus, by balancing the heating of the tip ensuing from the laser with the tip’s cooling via warmth flowing into the goal pattern, it’s viable to quantify a fabric’s thermal transport traits level by level.

In a brand new research reported within the Journal of the American Chemical Society, researchers from Tokyo Tech described a serendipitous but essential discovering whereas making use of SThM. The researchers had been making use of an SThM technique to quantify the thermal transport properties of self-assembled monolayers (SAMs).

Such samples consisted of alternating stripes of every of the three doable pairs between n-Benzenethiol, n-Butanethiol and Hexadecanethiol. Along with making use of the usual contact-based SThM technique, the scientists tried utilizing a non-contact regime as nicely, through which the tip of the scanning thermal microscope was positioned above the pattern with out touching it. All of a sudden, the researchers realized this non-contact regime had some severe capability.

Within the contact SThM regime, warmth flows instantly from the tip to the pattern. Alternatively, within the non-contact SThM regime, the one warmth switch between the tip and the pattern takes place via warmth radiation.

By experiments, the staff found that though the contact regime is greatest for imaging the thermal transport traits, the non-contact regime is very delicate to the true size of the molecules “protruding” from the substrate. Thus, the mix of the non-contact and get in touch with regimes provides an all-new method of creating topographic and thermal transport photographs of a pattern concurrently.

Moreover, the non-contact technique has advantages over different well-established microscopy strategies.

The non-contact SThM strategy is totally non-destructive, not like different strategies like atomic drive microscopy, which does require contact between the scanning tip and the pattern and thus has a mechanical impression that may injury smooth natural supplies.

Shintaro Fujii, Examine Lead Writer and Affiliate Professor, Tokyo Institute of Know-how

On the entire, the understanding provided by this research will set the stage for novel technological progress and a deeper comprehension of supplies on the nanoscale.

Our work not solely is the primary to supply thermal photographs of natural SAMs, but additionally supplies a brand new approach for investigating thermal transport properties, which can be important for thermal administration in varied forms of nanodevices,

Shintaro Fujii, Examine Lead Writer and Affiliate Professor, Tokyo Institute of Know-how

This research may assist researchers clarify a number of mysteries behind thermal phenomena.

Journal Reference:

Fujji, S., et al. (2021) Visualization of Thermal Transport Properties of Self-Assembled Monolayers on Au (111) by Contact and Noncontact Scanning Thermal Microscopy. Journal of American Chemical Society.