One of the most mysterious features of quantum mechanics is that if two particles (or photons) interact at some point in time then the properties of these particles will remain connected at future times. A consequence of this is that determining the quantum state of one of the particles simultaneously determines the quantum state of […]
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. Hence, if catalysts take the form of nanoparticles, any physical feature of the nanoparticle interacting with the reacting molecules may […]
Condensed matter • Materials • Nanotechnology • Quantum physics
Imagine a military regiment in formation. That we will call symmetry. Now imagine the same regiment when it is dismissed by the commanding officer: at once the soldiers disperse and tend to form domains (groups) or pairs. Hence, we can say that the symmetry is spontaneously broken. Both superconductors and ferromagnets are examples of electron […]
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 positioned at random and have no long-range ordered pattern. These […]
The ability to examine the vibrational spectra of liquids with nanometer spatial resolution will greatly expand the potential to study liquids and liquid interfaces. After all, modern technology, including many manufacturing processes, and science depend on understanding the detailed interactions at such nanoscopic interfaces. Actually, a better comprehension of the fundamental properties of the commonest […]
Imagine that we have a conductor or a semiconductor through which a current is flowing. Then we apply a strong transverse magnetic field. As a result, we can measure a potential difference at right angles to both the current and the field caused by the deflection of charge carriers by the field. This effect was […]
Condensed matter • Materials • Physics • Quantum physics • Theoretical physics
The revolutionary theory of topological quantum chemistry , a description of the universal global properties of all possible band structures and materials, diagnoses topological phases based on elementary band representations. A set of bands is topological if it lacks an “atomic limit” that obeys the crystal symmetry (and time reversal, if desired): formally, an atomic […]
Condensed matter • Materials • Nanotechnology • Physics • Quantum physics • Theoretical physics
Chemists have a range of different spectroscopic techniques to study organic molecules. All of these techniques are based on spectra generated by a range of electronic transitions and vibrations, key excitations in matter, the study of which provides information about characteristics of materials and, therefore, allow their identification. In this context, one of those spectroscopic […]
Condensed matter • Materials • Nanotechnology • Physics • Theoretical physics
Most of the theories describing dynamical processes at surfaces rely on the validity of the adiabatic Born-Oppenheimer approximation. What does this mean? We have already seen that adsorption commonly is understood as the reversible binding of molecules and atoms from the gaseous or liquid phase on surfaces, mostly of highly porous adsorbent media. In chemisorption […]
Condensed matter • Materials • Quantum physics • Theoretical physics
The wave nature of light expresses itself in the propagation all over space, showing an intrinsic limitation to be localized beyond the so-called diffraction limit which is of the order of half the wavelength of the photons propagating. However when interacting with matter, light often gets reflected, diffracted, scattered or absorbed depending on the interactions […]