Cambridge University conducted experiments control chemical reactions occurring in individual atoms

Cambridge University conducted experiments control chemical reactions occurring in individual atoms
Picture for illustration only Due to the size of atoms and molecules at tiny sizes (few Angstrom, denoted A, 1 A = 1/10, 000,000,000 m), plus the number of atoms is extremely large in a substance, it is difficult to imagine a chemical reaction that takes place when mixing them together and how to control this process in each individual atoms. But researchers at the lab scientists named have made the earth to balance the Cambridge University Cavendish (UK) has made it hard to believe that a reality. Based on laser technology and ultra-low temperature technology, they control the chemical reactions occurring at the atomic level. Before you introduce tinhte on innovative projects of the University of Cambridge, I will present some concepts of physical-chemical for people to track.   Knowledge base   Atoms are composed of positively charged nucleus in the center and (s) in the outer shell electrons. Electrons move around nuclei with very large velocity creates a negatively charged region of space nuclear wrapped or we called the electron cloud.   In normal conditions electrons in atoms (or ions) will be in different orbits where they do not lose energy, or the steady state. So when a certain profile provides energy (heat, light ...) to steady-state electron jump higher, or jump out of atoms, and atoms put into a state of excitation. The way different effects can cause the different excited states. In this state, atoms and ions will have more energy than when they are in the ground state (normal atoms). However, they tend to release energy and return to more stable ground state after a certain time. In the case of electron escape from the attraction of nuclear links between it and the nucleus breaks down, providing the energy required for this process is called ionization energy.   Now we will see what happens when substances react with each other: the breaking process and create new links between the substances. Similar to the case of link between the nucleus and electrons, to break the link between the atoms (molecules), the need to provide a corresponding energy. Conversely, when two independent atoms linked together, they give off a certain energy. For example, the protons combine with electrons to form hydrogen atoms, it will radiate heat. When chemical reactions take place, the original link was broken and new bonds are formed. Normally the energy released from the new link will be greater than the energy to break the old link, then the reaction is called exothermic. The energy from the exothermic reaction can be in the form of the product kinetic energy (moving faster or increase the mixture temperature) or light (photon radiation).     At the Cavendish Laboratory for Experimental   In normal conditions, when two of the appropriate chemicals are mixed together, the chaotic thermal motion, or from human agents would make the atoms, molecules interact and cause side application. However, when ultra-low temperature and with a few atoms, the situation is completely different than what we imagine. The atoms move very slowly so they do not have enough kinetic energy needed to overcome the Coulomb repulsion between the negatively charged electron cloud surrounding the outside. The result is the reaction will not occur.   So, instead of done with pairs of atoms-atoms, the research team at Cambridge considering ion-atom pairs. We know that the ions formed when atoms lose or receive one or a few electrons, so it will no longer electrically neutral particles again. When an atom and a positively charged ions in slow motion, Coulomb attraction between them will push to make the two particles approach each other and then the combination will cause a chemical reaction.   Based on that principle, the researchers conducted an examination of the interaction between the positively charged ytterbium ion (Yb +) and the electrical neutral rubidium atoms (Rb). In the experiment, the researchers used a laser to create the Yb + ion with two different excited states. They selected these states because they survive long enough before it becomes the ground state and to control it reacts with Rb atoms.   To test the reaction is taking the form of kinetic energy release or photons, the Cambridge scientists first conducted experiments in the dark by turning off the laser beam after it is used to ionize the atoms Yb . The results show that this reaction releases energy in the form of kinetic energy. However, due to the energy of Yb + in excited states is metabolized, it creates the following molecules move faster response than usual. In some cases, these molecules may have enough speed to escape the attraction between other components and collided with the average of laboratory equipment. Then one can accurately measure the velocity and energy is how much they get.   In the second experiment, the team continued reference beam and Rb atoms and ions to regulate the interaction between them. By tuning the frequency of the laser radiation, they found that the reaction rate change as well as the quantum state of the particles will vary according to product.   However, the measurement results do not always indicate the reaction can also occur. A number of collisions between Rb and Yb + hit to make a move electron from Rb atoms into Yb + ion. Then the scientists obtained a Yb atoms are electrically neutral and Rb +. This process is called the charge change.   Through series of experiments, scientists found that the relative orientation changes between the electron spin and nuclear spin can cause different effects on the quantum state of the reaction products. This is a very new phenomenon, by far the views are unified only by the chemical reaction effects of the atomic shell and the kernel does not play a role any impact.   Upon investigating the phenomenon of charge exchange, affects the atomic spin, and other properties appear in the reaction process, the scientists gave a full explanation for how these questions quantum state can be combined together to cause chemical reactions at extremely low temperatures. Furthermore, by using the single atom, they can create a clean environment to avoid the influence of environmental or other impurities can affect test results.   The work of the research team at Cambridge University have been published in the prestigious journal Nature Physics.   Source: ArsTechnica ...


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