Usually, the concept of exciton is linked to that of nonmetallic crystal: an electron-hole pair in a crystal that is bound in a manner analogous to the electron and proton of a hydrogen atom. It behaves like an atomic excitation (hence the name) that passes from atom to another and may be long-lived. Exciton behaviour […]
The pairing of ions of opposite charge is one of the dogmas in chemistry and ion-pairs or ionic interactions often govern chemical reactions or more particularly such processes as synthesis or catalysis. Usually, there is no doubt that ions possess opposite charges. This is why the recent report on the existence of cation-cation pairing by […]
As the search for renewable energy sources has intensified, the discovery of efficient and cheap technologies for exploiting the energy from the sunlight has emerged as a key challenge. Higher efficiency plays an increasingly important role in making competitive solar cell designs as the price of silicon continues to drop. At present, the actual silicon […]
We are all familiar with the equation of ideal gases: PV = nRT. To deduce this equation, an ideal model of the gas is considered. In this model, gases are composed of particles so tiny compared to the volume of the gas that they can be considered zero-volume points in space, and there are no […]
¨The chemical bond¨ is one of the most often used concepts in chemistry. It is also one of the eldest terms since the first definition of chemical bond comes from the studies of G.N. Lewis who published his classical paper on interactions between atoms in 1916 . Lewis stated that ¨ we shall say that […]
Chemistry • Condensed matter • Materials • Physics • Quantum physics
Minimizing losses in any kind of electronic device is always important, but it is paramount in nanoelectronics. Still, most of the phenomena that lead to inefficiencies in the operation of these nanodevices are poorly understood. Consider the case of quantum dots. A quantum dot is a nanometric crystalline structure of semiconductor materials. In a quantum […]
In the standard representation of the periodic table, we find below two separated rows of elements. Their chemistry and electronic configuration belong to a group three element, so what these two separated rows really mean is that in this representation of the table they are all located on top lanthanum and actinium, three-dimensionally building a […]
When two superconducting materials are separated by a very thin (less than 10-8 m or 10 nanometers) layer of an insulating material at very low temperature some peculiar electrical effects can be detected called Josephson effects. If normal conducting metals are separated by such a barrier in that conditions it is possible for a small […]
The role of molecular hydrogen (dihydrogen) in reactions of organic and inorganic chemistry is very well known . One can mention numerous reactions playing the key role in biochemistry, like for example processes in microorganisms, or the commonly known addition of H 2 to organic compounds. It is worth to mention that dihydrogen as an […]
We are all familiar with rust. Rust is an iron oxide, usually red, formed by the reaction of iron and oxygen in the presence of water or air moisture, and it is a clear sign of metal corrosion by oxidation. Oxidation is a ubiquitous phenomenon that proceeds via the electrochemical interaction of ambient oxygen molecules […]