Successful relationships between molecules - just like human relationships - require several basic conditions: first the molecules must encounter each other, and after the encounter they must be provided with a minimum period of time for a chemical reaction to occur.
These are two problems faced by Dr. Edwards Narevičius, from the Department of Chemical Physics in the Faculty of Chemistry. Dr. Narevičius is interested in the quantum phenomena that manifest themselves in chemical reactions, when they occur at very low temperatures - close to absolute zero. To study these phenomena, which are not manifested at higher temperatures, he develops methods that allow the molecules to be cooled, and in the process also provide the conditions required for meeting and interacting between them. "Unlike cooling atoms, which is relatively simple, cooling molecules to a temperature close to absolute zero is complicated," he says. "Molecules have many energy levels and also different types of movement - such as vibrations and rotations - which make cooling difficult."
How are molecules cooled? The most common method was developed about half a century ago, and won its inventors - Dudley Hershbach and Yuan Li - the Nobel Prize in Chemistry for 1986. In this method, called supersonic beam, a beam of the molecules they wish to cool is created, while they are carried in a cold gas. When the gas is allowed to be released under high pressure into a vacuum - it cools (for the same reason that the release of cooking gas causes the gas pipe to cool and the accumulation of ice on top of the pipe). This method is simple, easy and cheap to manipulate, and it is possible, by means of it, to cool a substance that is at room temperature (about 300 degrees Kelvin) to a temperature of one tenth of a degree above absolute zero. By running two beams opposite each other, it is possible to study the chemical reaction between two molecules, which occurs at the meeting point of the beams. However, this method has a significant drawback, which originates from the fact that energy is never lost: the energy released from the system during the cooling process becomes the energy of movement, and the beam accelerates to a speed that may reach up to two kilometers per second. Because of the high speed, the duration of the encounter between the two beams is extremely short - which makes it difficult for a chemical reaction to form, complicates its monitoring, and even affects the reaction products. "Our goal is to take the cooled molecules in the beam, and eliminate the acceleration effect - and thus enjoy the advantages of the method, and eliminate its disadvantages," says Dr. Narevičius. His method for stopping molecules and capturing them - which he began to develop during his post-doctoral research in Mark Reisen's group at the University of Texas at Austin - is similar to Gerard Mayer's development, which has existed for a decade, called the Stark decelerator. But while Meyer's method slows down the molecules gradually using pulses of an electric field, Dr. Narevičius' method is based on pulses of a magnetic field. The magnetic field, he discovered, is effective for a larger range of substances - any molecule or atom that has a constant magnetic moment. But this method also has its own disadvantages: during the deceleration, large losses of material are caused, and the molecules disperse and move away from each other. These individual molecules - similar to the fast molecules - have difficulty "recognizing" other molecules, and developing significant relationships that will lead to a chemical reaction.
To try to overcome this problem, Dr. Narevičius develops a magnetic trap - a kind of cup that holds the molecules inside it throughout the process. The trap is built from two magnetic coils inside which a current flows in opposite directions. In this way, a "pit" is created which limits the movement of the molecules, and does not allow them to leave. For the trap to function properly - as anyone who has tried to run while holding a coffee mug knows - the deceleration must occur gradually, as sudden braking will cause the molecules to spill out of the trap. For this purpose, Dr. Narevičius developed a sequence of over 200 overlapping traps, which are activated gradually, one after the other, with the speed of the center of the trap gradually slowing down by 100 times. Preliminary findings obtained in his laboratory show that in this way it is possible to reach a speed of ten thousand g) g is the acceleration of the force on the surface of the Earth), and reach a utilization of about 30% of the material - compared to the number of tenths of a percent received so far.
Now that he has succeeded in creating a trap containing cooled and slow molecules, Dr. Narevičius plans to use the means he developed to learn about the relationships woven between them. He is particularly interested in combustion reactions - in which oxygen molecules are involved, as well as "self-collisions" of molecules of the same type. In addition, he wants to find ways to get even closer to the point of absolute zero, and to cool the molecules in the trap he created - whose temperature is currently 100 thousandths of a degree above absolute zero - to only one thousandth of a degree, or even less.
personal
Edwards Narevičius was born in 1973 in Vilnius, Lithuania. He reached his first scientific achievements as a teenager, when he won first place in the Soviet Olympiad in chemistry for high school students. After that, he immigrated to Israel and completed his bachelor's degree (1995) and third degree (2002) in chemistry at the Technion, and at the same time served in the IDF as a weapons developer. Despite his education as a theoretical chemist, he gradually became an experimenter.
In the years 2005-2000, he worked as a senior scientist at the start-up company OpTun Inc, which develops optical communication components, where he developed and patented an optical switch that is now used as a component in various optical devices, and then embarked on post-doctoral research at the University of Texas at Austin, where he began his research dealing with the slowing down and capture of molecules and atoms.
In 2008 he joined the Department of Chemical Physics at the Weizmann Institute of Science.
Dr. Narevičius is married to Yulia, an electrical engineer, and has two sons: Yoav, six years old, and Idan, three years old. In his spare time he practices the martial art of kung fu and plays the piano.
