Information storage devic

An ion beam causes secondary electrons to be ejected from a metal surface. These secondaries can be measured as an electric current directly through a Faraday cup or indirectly after amplification, as with an electron multiplier or a scintillation device. These ion collectors are located at a fixed point in a mass spectrometer, and all ions are focused on that point — hence the name, point ion collector. In all cases, the resultant flow of an electric current is used to drive some form of recorder or is passed to an information storage device (data system). 

BiaxiaHy orieated PPS film is transpareat and nearly colorless. It has low permeability to water vapor, carbon dioxide, and oxygen. PPS film has a low coefficient of hygroscopic expansion and a low dissipation factor, making it a candidate material for information storage devices and for thin-film capacitors. Chemical and thermal stability of PPS film derives from inherent resia properties. PPS films exposed to tolueae or chloroform for 8 weeks retaia 75% of theh original streagth. The UL temperature iadex rating of PPS film is 160°C for mechanical appHcatioas and 180°C for electrical appHcations. Table 9 summarizes the properties of PPS film. 

FERROELECTRIC MATERIALS. The dielectric analogs of ferromagnetic materials. Their uses parallel those of ferromagnetic materials in such applications as magnetostriclive transducers, magnetic amplifiers, and magnetic information storage devices. Rochelle salt was the first ferroelectric material to be discovered and the barium titanale ceramics arc materials of this type... 

Special effects are envisaged when photochromic molecules are linked to the polymer backbone. Two approaches are possible as shown in Figure 6.13. Such a material would be extremely interesting for molecular information storage devices.60,61... 

Two-dimensional, metal-containing grids are of particular interest as their structures suggest the basis for the construction of information storage devices. Arrays on this type, in which the metal ions act as ion dots that might prove accessible by external stimuli, would be of smaller size than quantum dots. They have the potential advantage of self-assembling spontaneously and hence may eliminate the need for microfabrication. ... 

In general, it is most efficient for the microprocessor to access and store in the semiconductor main memory (DRAM) alone because the DRAM access time is < 100 ns. However, DRAM is volatile and any information in the DRAM is lost once the computer is turned off. Thus, lower level of information storage devices is essential. The latter may include magnetic hard disc, magnetic floppy drives, etc. As a rule, the higher-level storage media are... 

The majority of Mdssbauer experiments that are conceived to elucidate problems of chemical structure make use of velocity modulated spectrometers. Most frequently, these are of the constant acceleration type, in which equal time intervals are spent in equal velocity increments. The primary information storage device for such spectrometers is commonly a multichannel analyzer operated in the multiscaler mode. Since the minimum observable line widths (2rnat= hf ) for S7Fe and 1,9 Sn are 0.1946 and 0.6193 mm/s, respectively, and since on the order of at least 5-10 data points on each side of the resonance maximum are... 

DNA- and porphyrin-based, linked-ring molecular chains (catenanes) as information storage devices [28, 29]... 

Two-dimensional grid-like structures are of particular interest, as their architectures may serve as a basis for the construction of information storage devices (33). By addressing the metal ions photo- or electrochemically, it might be possible to inscribe into the arrays patterns which could be read out non-destructively (7). Such ion dots would still be of smaller size than quantum dots (34), and they would form spontaneously by self-assembly, not requiring microfabrication. 

In addition to the above inductive technologies for information storage, devices based on the Faraday or Kerr effects are being developed. The aim is to increase two of the most appreciated characteristics in storage technology devices data density and access time. The storage capacity of a magnetooptical disc is currently 600 MB (files, 1991). An additional characteristic of these methods is that the wear problem is virtually eliminated. 

A further major use for LCPs is in the area of opto-electronics. Their usefulness here arises partly from their ability to incorporate the properties of more conventional liquid crystals, which are fluid at ambient temperatures, within a material that does not need to be confined in a cell. When a small-molecule liquid-crystalline material is cooled to form a solid it usually crystallises in such a way that any structure within it, i.e. orientation of the molecules, is lost. LCPs can, however, form glasses in which orientation induced above the glass transition can be retained. This leads to the possibility, among others, of information-storage devices. For instance, the heating effect of a laser beam, with or without the simulta-... 

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