Charging friction

Luminescence is a broad term referring to the emission of light by any process exclnding incandescence. In principle, luminescence can be classified based on excitation mode (absorption of photon, chemical reaction, injection of charge, friction, sound waves, etc.) or the type of excitation state (first excited singlet state or lowest triplet state). Here, we limit our discussion to the two forms of photoluminescence, which are fluorescence and phosphorescence (Figure 1). 

An alternative approach is to consider ions of charge z e accelerated by the electric field strengtii, E, being subject to a frictional force, Kj, that increases with velocity, v, and is given, for simple spherical ions of... 

Some engineers (who normally are precise and specific) are charged with the task of approximating the friction losses (the Hfand Hv) in... 

The earliest information dealing with this phenomenon dates back to 600 B.c. It was found that a piece of amber after it had been rubbed was able to attract small fibers. More recent observations are from the 17th century, when William Gilbert noticed that amber, sulfur, and other dielectrics charged by friction could attract smoke. Similar observations were made by Boyle (1675) and Otto von Guericke (1672). Francis Hauksbee (1709) reported that he had discovered a phenomenon which is now called ionic wind or electric wind. Ionic wind and the glow from the corona discharge was discussed by Isaac Newton (1718). 

Electrophoretic techniques are based on the movement of ions in an electrical field. An ion of charge q experiences a force F given by T = Eq/d, where E is the voltage (or electrical potential) and dis the distance between the electrodes. In a vacuum, T would cause the molecule to accelerate. In solution, the molecule experiences frictional drag, iy, due to the solvent ... 

The mechanism by which analytes are transported in a non-discriminate manner (i.e. via bulk flow) in an electrophoresis capillary is termed electroosmosis. Eigure 9.1 depicts the inside of a fused silica capillary and illustrates the source that supports electroosmotic flow. Adjacent to the negatively charged capillary wall are specifically adsorbed counterions, which make up the fairly immobile Stern layer. The excess ions just outside the Stern layer form the diffuse layer, which is mobile under the influence of an electric field. The substantial frictional forces between molecules in solution allow for the movement of the diffuse layer to pull the bulk... 

Two inventions in the 1740s changed the electrical scene dramatically. One was the frictional machine, which made it possible to generate continuous streams of electricity relatively easily the other was the condenser, or Leyden jar, which made possible the storage and sudden discharge of substantial quantities of electric charge. 

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