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Observations: rolling versus sliding

Observations beyond the range of the naked eye require more deliberate and cautioned interpretation of what isobserved. Specifically, factual and accurate information must be discerned out of various interferences that can lead tounsubstantiated conclusions. The Tour group had to surmount these uncertainties to conclusively show that the nanocars underwentrolling, rather than sliding, translational motion.

Nanocar translational movement across a gold surface at 200°C. The pivoting of the molecule’s motion is due to out-of-sync rotation of wheel movement. Thepicture indicated path occurred over a minute period (images captured ever minute by STM). Reprinted with kindpermission from Dr. Kevin Kelly<picture courtesy of Rice University Office of Media Relations>.

The choice of a gold surface enabled temperature dependent adhesion to the surface, and allowed targetedobservation of specific molecules. In the picture to the left, you see several nanocars spread out along the Au(111) surface. As theresearchers increased the temperature to 200°C, the cars began to move at such a rate that they noticeably displaced from their originalposition in a period of one minute (figure 8). This indicates that 200°C is a viable temperature for imaging nanocars on gold with STM. However, imaging of the cars at temperatures above 225°C is currently impossible due to the rapid motion of the molecules at thattemperature. The nanocars are moving too quickly to be imaged by the one-minute capture rate of the STM. Once the system was heated to300-350°C, the car began to decompose. These observations indicated that motion of the nanocars was dependent on temperature.

It was also observed that the cars did not exclusively undergo translational motion, but also rotated. In theimage to the right, it can be observed that the cars pivot as they move across the frame, changing direction without moving forward. TheTour Group explained this rotation as an inability to synchronize the rotation of each wheel.

The Tour Group also observed three-wheeled molecules, or trimers, which they found useful inproving rotational motion of the C60 molecules. If the cars’ movement were in fact due to rotation, then the trimer would not be able tomove translationally due to the fact that the three wheels cannot rotate in a coordinated manner, that is no two wheels can rotate thesame parallel plane. This supports the idea that the C60 molecules are rotating, as opposed to sliding. To strengthen their assertion, theresearchers heated a sample of the trimer molecules on the same gold surface to 225°C—a temperature at which the four-wheeled molecules rapidly moved out of the scanning range of the STM. Upon doing so,they observed that the trimers did not undergo significant translational motion, and remained within nanometers of their originalposition. This showed that both the wheels and axels of the trimer and nanocar allow for rotational motion, therefore substantiating theassertion that translational motion of the nanocar is due to rolling.

The researchers used an STM to pull the nanocar in order to see if there was preferential motion (ie. Due torolling). When the molecules were pulled perpendicular to the axles (Figure 9; frame a) the molecule moved in the direction of thepull. But, pulling parallel to the axles resulted in no translational motion in the direction of the pull (frame b). Lastly, by pullingperpendicular to the axles, the nanocar resumed its forward path (frame c).

Translational Motion of Pulled Nanocars on Gold Surface at 200°C. Frame (a) depicts the movement of a nanocar pulled perpendicular to its axles. Frame (b) indicates theinhibited motion that results from pulling parallel to the axles. Frame (c) is another instance of a pulling force perpendicular tothe axles. Reprinted with kind permission from Dr. Kevin Kelly<picture courtesy of Rice University Office of Media Relations>.

These experiments carried out by the Tour Group combined to substantiate the claim that the nanocars wererolling on the C60 wheels as opposed to sliding. This observation designates the molecule as the first nanocar capable of executing apredetermined, engineered motion. These experiments lay down a foundation of knowledge on the molecular mechanics of motion.Particularly, these experiments conclusively demonstrate rolling motion of the C60 on gold surfaces at a given temperature. This marksthe first step in a greater understanding of molecular motion as it applies to molecular manufacturing.

The future of the development of molecular manipulation

Molecular manipulation as a science has developed in steps. Its early steps involved movement of atoms and molecules,along with the ability to observe those movements. Later came engineered molecular components that carried out predeterminedfunctions, such as bearings and axles. At the present, nanocars are an example of the developments in motility and function of integratedcomponents that serve a unified purpose. But more importantly, nanocars are an indicator of developments to come. They are usheringin an era of deliberate and controlled motion at the molecular level.

Questions & Answers

How we are making nano material?
what is a peer
What is meant by 'nano scale'?
What is STMs full form?
scanning tunneling microscope
what is Nano technology ?
Bob Reply
write examples of Nano molecule?
The nanotechnology is as new science, to scale nanometric
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
what school?
biomolecules are e building blocks of every organics and inorganic materials.
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
sciencedirect big data base
Introduction about quantum dots in nanotechnology
Praveena Reply
what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
Damian Reply
absolutely yes
how to know photocatalytic properties of tio2 nanoparticles...what to do now
Akash Reply
it is a goid question and i want to know the answer as well
characteristics of micro business
for teaching engĺish at school how nano technology help us
How can I make nanorobot?
Do somebody tell me a best nano engineering book for beginners?
s. Reply
there is no specific books for beginners but there is book called principle of nanotechnology
how can I make nanorobot?
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
what is the actual application of fullerenes nowadays?
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
Mostly, they use nano carbon for electronics and for materials to be strengthened.
is Bucky paper clear?
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
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Source:  OpenStax, Nanotechnology: content and context. OpenStax CNX. May 09, 2007 Download for free at http://cnx.org/content/col10418/1.1
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