Atom scattering at low energies has a long history as a useful probe of surface properties. The most common atomic projectiles are helium atoms formed into a monoenergetic beam directed toward the surface with energies in the thermal range, meaning kinetic energies less than 100 meV. From ordered surfaces the scattered spectra consist of sharp […]
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 […]
Condensed matter • Nanotechnology • Physics • Quantum physics • Theoretical physics
The electronic wave function of an n-electron molecule depends on 3n spatial and n spin coordinates. In a sense, the wave function of a many-electron molecule contains more information than is needed and is lacking in direct physical significance. This has prompted the search for methods that involve fewer variables than the wave function and […]
The scattering of conduction electrons in metals owing to impurities with magnetic moments is known as the Kondo effect, after Jun Kondo, who analysed the phenomenon in 1964. This scattering increases the electrical resistance and has the consequence that, in contrast to ordinary metals, the resistance reaches a minimum as the temperature is lowered and […]
We usually think of crystals as composed of different atoms in certain proportions, this proportion being the molecular fórmula that represents the crystal. However, it is not surprising that any molecule could be the basis of a crystal structure, whether a simple molecule such as methane, or a complicated molecule such as a protein or […]
We usually think of nature as existing completely independently of us and possessing a definite reality and behaviour even when we are not observing it. For instance, you assume that the world outside of the place where you are now sitting still exists pretty much as it was when you last observed it. Certainly this […]
Two of the hot topics in science an technology nowadays are related to Computer Science. They are Artificial Intelligence (AI) and Quantum Computing (QC). AI is a really old field, as humanity has dreamed of having autonomous machines for decades. Quantum Computing is not as old as AI. It is considered that the idea of […]
The wave–particle dualism is a fundamental aspect of quantum mechanics. But, in order to explore this dualism properly and what it means for our image of atoms, it is necessary to review some ideas of probability. In some situations, no single event can be predicted with certainty. But it may still be possible to predict […]
Condensed matter • Physics • Quantum physics • Theoretical physics
You may have read somewhere that atoms are actually made up mostly of empty space. The usual description goes more or less as follows. At the centre of each atom there is a very tiny nucleus, which carries all of the positive charge and nearly all of the mass of the atom. Surrounding the nucleus […]
What only a decades ago seemed impossible for chemists, determining the chemical structure of molecules directly from experimental images, is now routinely done. Not only that, the information about bond order, intermediates, and products of on-surface chemical reactions or charge distribution within molecules can also be quantified from those images. Two main techniques have made […]