A chemical compound or molecule consisting of two identical simpler molecules is a dimer. If one of the simpler molecules is excited while the other is in its ground, non-excited, state we talk about excimers. They are excited dimers which are non-bonding in the ground state. Thus, excimers can be considered evanescent quasi-particles that typically […]
Luthiers still use Chladni figures in the design and construction of acoustic instruments such as violins, guitars, and cellos. The technique invented by the German physicist and musician Ernst Chladni (1756–1827) shows the modes of vibration under forcing. The backplate of the instrument is covered with flour or sand, and bowed until it reached resonance […]
Chemistry • Condensed matter • Materials • Physics • Quantum physics
Graphene is a two-dimensional allotrope of carbon made of hexagons. In February 2015, penta-graphene, only made of pentagons, was theoretically proposed as another two-dimensional allotrope of carbon . Apparently, it is dynamically, thermally, and mechanically stable, exhibiting a large band gap (graphene is gapless). However, an exhaustive experimental search has been inconclusive, resulting in doubts […]
Condensed matter • Materials • Nanotechnology • Physics • Quantum physics
Silicon surfaces of crystalline solids are part of conventional electronics, but their exploitation in novel materials combining two-dimensional electron states (2DESs) and magnetism, which play an important role in the development of next-generation electronics, still remains elusive. The appearance of 2DESs at surfaces or interfaces and their interplay with magnetic degrees of freedom may open […]
Author: Leire Gartzia Rivero got a Chemistry degree and completed her Master studies in “New Materials” at the University of the Basque Country. She holds a Ph.D. in Materials Science and Technology obtained at the same university, in the Molecular Spectroscopy Laboratory, where she focused on the spectroscopic characterization of photoactive nanomaterials based on energy […]
Nanoparticles of certain metals, like gold or silver, have attracted substantial interest in recent years owing to their ability to support localized surface plasmon resonances (collective oscillations of conduction electrons). These plasmonic excitations allow manipulation of light at the nanoscale and have enabled technological advances ranging from improved catalytic and photovoltaic cell efficiencies to sensitive […]
A phase may be defined as a homogeneous portion of a system that has uniform physical and chemical characteristics. Every pure material is considered to be a phase; so also is every solid, liquid, and gaseous solution. For example, a sugar–water syrup solution is one phase, and solid sugar is another. Each has different physical […]
We saw that one of the devices based on semiconductors are photocells. A photocell working in reverse is also useful. If a conduction electron in an n-p diode happens to fall into a hole, it will emit the excess energy as a photon, much as an electron would do in an atom as it jumps […]
A new vista in spintronics was opened in 2004 with the observation of the spin Hall effect in GeAs at 20 K by David Awschlom and his group. In the spin Hall effect the electrons of a charge current flow in a nonmagnetic conducting material in the absence of an external magnetic field. An applied […]
Let’s take a p-type semiconductor with a very clean surface and place it right next to the clean surface of a n-type semiconductor. This type of device is called an n-p junction diode , or simply a diode . What happens? Scientists realized that the electrons in the conduction band of the n-type semiconductor are […]