The Nanocar Race Is

PRESS KIT I PARIS I APRIL 4, 2017 NanoCar Race, the first international molecule-car race A CNRS event Contact CNRS Press Officer l Alexiane Agullo l T + 33 (0)1 44 96 43 90 l [email protected] 1 Contents The Nanocar Race is: A catalyst for research ………………………………………………………………………………………………... 3 Experts in molecular engineering …………………………………………………………………………………... 4 The first steps of "atom technology" ………………………………………………………………………………… 4 Join the race! A one-of-a-kind microscope ……………………………………………………………………………………......... 5 Why a racetrack made of gold? ……………………………………………………………………………………... 6 The process ……………………………………………………………………………………………………………. 6 The rules ……………………………………………………………………………………………………………….. 8 The organizers ………………………………………………………………………………………………… 10 The teams ………………………………………………………………………………………………………... 11 Resources ……………………………………………………………………………………………………….. 22 2 The Nanocar Race is: A catalyst for research The Nanocar Race—and associated development of nanocars—promotes research in synthetic chemistry, as well as the construction of increasingly high-performance microscopes and the control of molecule- machines. Beyond the competition itself, every stage of the organization of the race, along with every nanocar synthesis and strategy for evaporation and propulsion, has already been or will be the subject of scientific publications, providing the physics and chemistry community with answers to unresolved questions in the field. Researchers have thus had to contend with many unknowns; for instance, why do scanning tunneling microscopy images ensure the reconstruction of molecular orbitals1, thereby enabling the drivers to identify their nanocar instead of an unrecognizable jumble of electronic states? These questions are at the heart of the event, as nanocars cannot take part in the race without being properly imaged by the CEMES-CNRS scanning tunneling microscope. Other questions arise: why does a quantum object such as a molecule-motor measuring 1.5 nm in diameter, behave in an almost classical2 fashion when it is placed on a surface? Can this motor run in only one direction? How can the engine power of the molecule-motors that equip each nanocar be measured and calculated? Inelastic phenomena, in which a very small proportion of the total electrons transferred relinquish a few quanta of energy to the nanocar (thus enabling it to move forward or turn), are very little known. This is one of the challenges of the Nanocar Race, as each participating vehicle must be propelled using such phenomena, which supply the molecule with small amounts of energy. The challenges addressed by researchers in preparing for this race will be so many steps forward in new fields of chemistry and physics. Each team will leave with new skills, data, and know-how that will one day contribute to the development of surface chemistry (which enables chemical synthesis directly on a particular surface), for example, as well as to the establishment of new rules for designing molecule- machines, and to a new science of surfaces known as membrane science, which could make it possible to deposit a molecule-machine on the surface of a cell or to control the movement of a single molecule in a liquid. 1 In chemistry, a molecular orbital is a mathematical function describing a molecule's electronic states. This function can be used to calculate physical or chemical properties, such as the probability of finding an electron in a specific area. 2 A motor is either classical—which is to say that the movement is created by the rotation or the flip of a chemical group—or quantum, which is when the movement is created by the passage of electrons through the molecule's different electronic states with a certain probability. 3 Experts in molecular engineering A central issue in molecular engineering is to ensure the proper functioning of the desired molecular mechanism, and to succeed in controlling a change in the molecule's structure. A series of movements are being sought, such as the flip of a chemical group in the manner of a switch, the spinning of a molecular rotor, the closing of molecular pliers to grasp an atom, the stretching of a molecular arm to reach for an atom or small molecule far away on the surface—all without touching the neighboring molecule, which may be only a few nanometers away. For the Nanocar Race, this entails moving and steering a nanocar for 36 hours. Each team used complex chemical syntheses to develop each vehicle. Months of synthesis, modeling and tests were needed to design and drive a high-performance nanometric racing car. High command of molecular engineering is therefore essential to create the best possible machine. The years to come will probably see the use of such molecular machinery—activated individually or in synchronized fashion—to manufacture common devices. It could also be of great use in the atom-by-atom deconstruction of industrial and urban waste, or the capture of energy, for example. The first steps of "atom technology" Beyond hosting the Nanocar Race, the CEMES-CNRS four-tip microscope will eventually enable the atom- by-atom construction of the electronic circuits of the future, whether classical or quantum, as well as their characterization. It will also make it possible to measure the engine power of a single molecule-motor with the goal of driving silicon nanogears. This is one of the first steps toward a genuine "atom technology," in which electronic chips will be built atom-by-atom, with a precision on the order of a picometer.3 The development of multi-tip instruments like the one at the CEMES-CNRS, motivated by the organization of the race, will in the long run enable the synchronization of a large number of molecule-motors, which should also increase their engine power, for example to store or capture energy on a hot metallic surface. 3 1 pm = 10-12 m (or a billionth of a millimeter). 4 Join the race! A one-of-a-kind microscope The nanocar race will take place in a unique instrument, the LT-Nanoprobe, built by Scienta Omicron for the CEMES-CNRS. The instrument consists of four scanning tunneling microscopes that can simultaneously and independently scan the same surface at low temperature and in an ultrahigh vacuum, providing atomic- scale images with a resolution of 2 picometers. This type of microscope (called STM) uses the quantum mechanics phenomenon known as the "tunnel effect." It can very precisely measure the distance between an ultra-fine metallic tip and a conductive or semi-conductive surface, through an electric current established between the tip and the surface for distances inferior to a nanometer. The tunnel effect that occurs at the atomic and subatomic scale indicates a quantum object's capacity to cross an energy barrier, even if its own energy is lower than the minimum threshold needed to cross this barrier. The CEMES's microscope is the only one in the world with four tips that can be independently controlled by four users on the same surface. The necessary adjustments to make it operational for the Nanocar Race posed a series of challenges to the researchers. First, they had to modify the microscope to simultaneously place four nanocars in the same spot, so that four drivers could move their vehicle at the same time on the same surface. It took three months for a specialized company to build the evaporator enabling this operation. However, only a single rotating shutter will be available in the ultrahigh vacuum: it will uncover the containers housing the nanocars one by one, and evaporate them on the gold surface. The researchers therefore invented a system of caches to divide the racetrack into four sections—one for each competitor. Finally, as all of this takes place in an ultrahigh vacuum, the researchers designed a mini lift with an exit carousel to position these caches. They also extended the tip mounts by 1 mm on each STM to allow for four simultaneous scans without the mounts touching one another. Modifications were also made to the steering system: the control software was divided into four distinct software programs, one for each tip, so that each team has its own driving seat. A great deal of preparation was necessary before the microscope's tungsten tips could be used. The procedure for preparing tips of this type has been standardized over the past few decades. After an electrochemical attack in a basic environment on a tungsten wire measuring 250 microns in diameter, the researchers obtain tips of approximately 100 nm in radius curvature, albeit oxidized. They must then mount the tips on a small stainless steel tube with a 250-micron internal diameter, called a "tip holder", which attaches the tip to the STM. Once attached, and before being placed in a vacuum, the tip is heated to between 200 °C and 400 °C to remove the oxide. These steps will be carried out at the CEMES in a specific preparation chamber installed in the laboratory before the start of the race. 5 Why a racetrack made of gold? The gold surface was selected for the race because most nanocars form few chemical bonds with this surface, regardless of their chemical composition. The race's four tracks must simultaneously be cleared of all molecules other than those competing. The researchers will do this by using the experimental atom manipulation technique discovered in 1989 by the pioneering research of D. Eigler at IBM, and which later featured in the work of J.K. Gimzewski and C. Joachim in 1996 with respect to the manipulation of large molecules. The gold surface will be prepared a first time across its 8mm diameter, and simultaneously tested by each team. The molecules will then be evaporated section-by-section on this surface. However, even with great care, molecules will be dispersed across the entire racetrack, and it is likely that some of them will end up in another competitor's section.

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