Category archives: CFM

When two photons with the same energy interact with a nonlinear material, they “combine” and generate a new photon with twice the energy of the initial photons. More precisely, two photons at the fundamental frequency are absorbed by a plasmonic structure to emit one photon at the second-harmonic frequency. This is called second-harmonic generation. Second-harmonic […]

We all know what glass is, don’t we? We just point to the nearest window and it is that transparent sheet. Humans have been producing glass for at least 6,000 years, way before they knew how to smelt iron. Actually, the chemistry is well known: to produce window glass we just heat a mixture of […]

Graphene nanoribbons (GNRs), are strips of graphene with ultra-thin width (<50 nm). Graphene ribbons, introduced as a theoretical model by Mitsutaka Fujita and coauthors to examine the edge and nanoscale size effect in graphene, have emerged as a promising material for nanoelectronics, as they combine many of the extraordinary properties of graphene with a high […]

In the quantum theory of many-body systems, collective oscillations are called collective excitations. In a quantum context, everything is quantized. Hence, collective excitations become quantized modes because of the cooperative motion of the whole system as a result of interactions between particles. They may be electronic excitations in atoms and are referred excitons. In most […]

A quantum dot (QD) is a nanometric crystalline structure of semiconductor materials. In a QD electrons are confined in a region of space, thus creating a well defined structure of energy levels that depends very much on the size and shape of the quantum dot. This structure resembles that of atoms, that is why sometimes […]

A catalyst is a substance that increases the rate of a chemical reaction without itself undergoing any permanent chemical change. As the catalyst itself takes part in the reaction it may undergo a physical change. Metal complexes are typically regarded as catalysts that convert organic substrates into more valuable compounds; however, to date, catalytic transformations […]

There are chemical compounds, called isomers, that have the same molecular formulae but different molecular structures or different arrangements of atoms in space. In constitutional isomerism the molecules have different molecular structures: i.e., they may be different types of compound, or they may simply differ in the position of the functional group in the molecule […]

Achieving room temperature superconductivity is among the most pursued but elusive goals of scientists. I n December 2014 researchers claimed to have observed superconductivity as high as 200 K in hydrogen sulfide at high pressure, breaking all the records thus far. This meant that cuprates could be knocked from their position as the highest temperature […]

Topological insulators are materials with special universal properties, which are protected against perturbations. Such properties are theoretically described by topology, a branch of mathematics concerned with the properties of geometrical objects that are unchanged by continuous deformations. Topological insulators are electronic materials that have a bulk band gap like an ordinary insulator but have conducting […]

Nonlinear processes are attractive in microscopy and spectroscopy since they can be excited with light in the near‐infrared, which offers several advantages, from a deep tissue penetration capability or a reduced photodamage due to the lower photon energy, to a spatially more confined probed volume, which can result in an improved lateral resolution. These processes […]