Conversion electricity into light

Because of its indirect bandgap, bulk crystalline silicon shows only a very weak PL signal at 1100 nm, as shown for RT and 77 K in Fig. 7.9. Therefore optoelectronic applications of bulk silicon are so far limited to devices that convert light to electricity, such as solar cells or photodetectors. The observation of red PL from PS layers at room temperature in 1990 [Cal] initiated vigorous research in this field, because efficient EL, the conversion of electricity into light, seemed to be within reach. Soon it was found that in addition to the red band, luminescence in the IR as well as in the blue-green region can be observed from PS. 

In a scintillation detector, a fraction of the energy deposited by the primary radiation in the detector is converted to light that, in turn, is converted into an electrical signal. Conceptually, the process can be divided into the scintillation process itself (energy —> light), the collection and conversion of the light into electrons... 

If the superconducting film developed at Cornell is ever put into a telecommunications system, those stats would pale in comparison. Fast as they are, fiber-optical pulses must work in three steps conversion of electricity to light and back to electricity, a process that is relatively slow. A superconductor transmitting electrical pulses alone could, theoretically, carry more than a trillion bits of information per second—enough to handle 15 million simultaneous phone conversations, or to transmit everything in print in the Library of Congress in a couple of minutes ... 

Selenium is also a photoconductor, a material that changes light energy into electrical energy. Furthermore, it becomes better at making this conversion as the light intensity or brightness increases. 

Photolumincscence is used in fluorescent lamps. This application was even used before the Second World War. The lamp consists of a glass tube in which a low-pressure mercury discharge generates ultraviolet radiation (85% of this radiation consists of 254 nm radiation). The lamp phosphor (or a mixture of lamp phosphors) is applied to the inner side of the tube. This phosphor converts the ultraviolet radiation into white light. The efficiency of conversion of electricity to light is in a fluorescent lamp considerably higher than in an incandescent lamp. 

Photomultiplier tube Electronic device contained within an evacuated glass envelope, enabling the photoelectric conversion of incident light at a metallic surface into electric current via a number of stages of amplification. 

The number of particles can also be determined by means of automatic electronic counters in conjunction with a microscope. The operation of these instruments is based on the conversion of a light signal from the particle into an electric current. This method can be used to determine the number and sizes of particles between 1 and 200 fim in diameter (coal, diamond, metal, and other dusts) [108]. 

Just as electrons can travel long distances through a wire, photons can travel under the whole Atlantic Ocean through a glass fiber. An important modem trend is to communicate via optical fibers, and therefore we need to be able to convert electrical energy into light, and back again. This chapter will cover some of those conversions. 

The conversion of solar light into electric power requires the generation of both negative and positive charges as well as a driving force that can push these charges... 

The involvement of LES in electrochemical processes may allow the conversion of electrical energy into light. This phenomenon, which is the reverse of the previously described photogalvanic effect, is called electrochemiluminescence (ECL). One of the most noticeable examples of ECL is that concerning Ru(bpy)3 in acetonitrile solution [57,58]. When cyclic square waves between the potentials of formation of Ru(bpy)3" and Ru(bpy)3 (figure 8) are applied at a Pt electrode immersed in the solution, a red luminescence is observed which continues indefinitely if the electrical potential is maintained. The reaction mechanism, illustrated in figure 22 involves reactions (56) - (59) ... 

Chemistry produces many materials, other than drugs, that have to be optimized in their properties and preparation. Chemoinformatics methods will be used more and more for the elucidation and modeling of the relationships between chemical structure, or chemical composition, and many physical and chemical properties, be they nonlinear optical properties, adhesive power, conversion of light into electrical energy, detergent properties, hair-coloring suitabHty, or whatever. 

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