The most famous equation of perhaps the entirety of physics history: E = mc2. The simple statement that energy is inherently connected to mass. There are many caveats and extensions that can be understood but the basics is just that. A particle will have an energy that is stored partly as mass and partly as kinetic energy. In nuclear reactions we have discovered processes which ultimately lose some amount of mass, this is converted into energy with explosive potential (as the equation tells us that every kilogram of mass will provide c2 Joule worth of energy). The process can also work in reverse. Provide a photon with enough energy and it could very well produce mass in the form of an electron and a positron most commonly.
Surface plasmons are the oscillating electrons that exist in a metals surface. They get excited very easily by any light that is incident on the metal. It is possible for an electromagnetic wave in the visible or infrared to be formed in interface between a metal and a dielectric (such as the air). This wave is called a surface plasmon polariton and can be produced when energy energy is provided in a direction parallel to the metal’s surface. These waves are very important for both research and technology especially their tendency to travel along the surface much like light travels along an optical fibre.
Muons are like electrons, but heavier. That is possibly the best description of them possible in so few words. Muons have a negative charge equivalent to an electrons, a spin of ±1/2 and can be found in many of the same Feynman diagrams as the electrons. This make their heaviness their defining characteristic as they have a mass 207 times greater than an electron’s. Of course this means it’s harder to accelerate a muon to particular speed but once it’s there, it’s unlikely to be stopped as easily as an electron. The transmissivity of a muon beam is considerably greater than that of an electron beam or an X-ray (their higher mass results in less deacceleration so less energy radiated). This means imaging of incredibly dense materials such as subterranean rocks or nuclear waste can be performed where an electron only method would struggle.
Geometrical frustration is a concept in the study of solid matter where a regular atomic lattice is disrupted by irregular interatomic forces. If there is a set of forces favouring a simple cubic arrangement and another favouring a hexagonal structure then these forces, which if were allowed to act alone would create a nice regular pattern, produce a much more complex structure described as frustrated. Geometrical frustration becomes of great relevance when studying magnetic effects on the quantum scale due to the arrangement of spins, which can be imagined as tiny magnetic fields either up or down in this case.
Optomechanical systems are nothing if not delicate. When the driving force (very literally) in a system is the pressure of incident light it is no surprise that forces being examined are on a minute scale. On a relevant diversion: the Nobel prize for physics has recently been announced to be for the discovery of gravitational waves which was where the development of optomechanics came from. The effects of optomechanics on the interferometric gravitational wave detectors had to be accounted for to analyse when the disturbance was actually caused by a gravitational wave. Now back to pure optomechanics. The sensitivity of electromechanical systems, which makes them so hard to set up, can actually be used as an advantage. All the best measuring equipment is delicate purely because it needs to be delicate to pick up the change its supposed to be measuring and this is where optomechancial systems can shine.
Although radioactive dating is often talked about another, no less important type of dating, luminescence dating, is not. Luminescence dating is used to study the last time a piece of rock was in the sunlight. It can only be used on materials seen as semiconductors, mainly quartz and feldspar as these both contain silicon, but if the date these rocks were buried is known then the date of the surroundings is also known. The dating works by looking at the number of trapped electrons present in the rock. You see crystal lattices can develop defects which in this case are called electron traps. As various radioactive decays occur in the rocks around them the ionising radiation produces electron-hole pairs within the lattice. The holes exist in the valence band and electrons exist in the conduction band and these electrons also can get trapped in the interband region caused by the defect. These electrons can then be released when light is shone upon the rock and so we can learn how long it has been in the ground based on the amount of charged stored within it.
In 2014 the Nobel prize for physics was given to three men whose combined work was the production of a blue light emitting diode. The reason that this was such a special achievement was the fact that when the blue LED is covered by a colour conversion layer made of various phosphors it can have an eventual output of white light. This is obviously ideal for almost all artificial lighting as white light is mirrors that which is produced by the Sun. Phosphors in general work by absorbing the incident blue light and then radiating light of a lower frequency through the promotion and relaxation of atomic electrons. However there is a problem. Although LEDs have only improved in reliability, energy efficiency and lifetime over the course of their development the phosphors used have remained limited to rare earth metals and their ions.