Beginning in 1928, Felix Bloch, an assistant to Werner Heisenberg in Leipzig, began to make some realistic assumptions in an attempt to formulate a more complete quantum mechanics of electrical conductivity. First, because he wanted to assign a definite momentum and energy to each of the electrons, but not a definite position or a time […]
During World War II the Germans relied on their strong chemical knowledge to overcome the limited access to critical raw materials that the circumstances of the war itself imposed. One of these raw materials was Chilean saltpeter (sodium nitrate), which was the base for explosives. The solution was to use a chemical process designed to […]
Common glass, used in windows or bottles, for example, is made by heating a mixture of calcium oxide (lime), sodium carbonate (soda), and silicon (IV) oxide (sand), resulting in a calcium silicate. This silicate is not a crystal but a solid in which atoms are random and have no long-range orderd pattern. These kind of […]
When we approximate two superconducting materials at low temperature, so that they are only separated by a very thin layer (less than 10 nanometres thick) of an insulating material, some new and very interesting electrical effects can be observed. If normal conducting metals are separated by such a barrier in that conditions it is possible […]
Gold is the quintessential noble metal. Its lack of chemical reactivity, particularly to acids and atmospheric corrosion, together with is rarity and malleability make it the precious metal it is since ancient times. Today, if we go for a description of gold in a chemistry textbook, we find something similar to this: A soft yellow […]
When light encounters molecules, the predominant mode of scattering is elastic scattering (Rayleigh). This scattering is responsible for the blue colour of the sky, for example. It is also possible for the incident photons to interact with the molecules in such a way that energy is either gained or lost so that the scattered photons […]
Imagine a very simple chemical estructure: 4 carbon and 1 nitrogen forming a ring, with no double bonds, just simple bonds between any two of them and with hydrogen. This compound is called pyrrolidine and is the base of very important biological and farmacological products. Pyrrolidine is found naturally in the leaves of tobacco and […]
Chemistry • Condensed matter • Materials • Physics • Quantum physics
Faster. That is the word that describes de evolution of electronics. Any new development has to be faster than anything before, if it is going to cope with the huge amount of information that the device where it may be incorporated will have to process in almost no time. Graphene has just demonstrated once again […]
Carbon has four valence electrons. To fill its octet, it requires four additional electrons, which can be obtained through the formation of four covalent bonds. Carbon forms single, double, and triple bonds to achieve a filled octet. As a result, carbon can have a tetrahedral, trigonal planar, or linear geometry, respectively. A unique feature of […]
A topological insulator is a material in which there is order associated to topology, i.e., the surface can conduct electricity but the bulk of the material is an insulator. In these last years topological insulators have received the attention of a large area of the scientific community thanks to their exotic properties. They are promising […]