Quartz amorphous

In this section we compare the theory of the preceding two sections with experimental measurements of infrared extinction by small particles. Comparisons between experiment and theory for spheres of various solids, most notably alkali halides and magnesium oxide, have been published in the scientific literature many of these papers are cited in this chapter. In most of this work, however, there is an arbitrary normalization of theory and experiment, which tends to hide discrepancies. For this reason, most theoretical calculations in this section are compared with mass-normalized extinction measurements. The new measurements presented here were made in the Department of Physics at the University of Arizona. A group of solids was selected to illustrate different aspects of surface modes. Results on amorphous quartz (Si02) particles, for example, illustrate the agreement between experi-... 

In practice, a convenient range of solid crystalline materials, which can be polished to optical flatness over manageable areas, exists and includes silicon, quartz, and sapphire. The equivalent transmission through a block of amorphous quartz or silicon is 10—15%. This has so far precluded them from use, and limited the application to crystalline substrates. In aqueous solution, the most commonly use contrasts are D20, H20, and water (H20/D20 mixture) index matched to the solid phase. In D20, the refractive index (or scattering length density) difference between that and the solid phase is significantly different for silicon, quartz, and sapphire (see Table 1). 

SYNS ACCUSAND amorphous quartz AMORPHOUS SILICA BORSIL P CRYPTOCRYSTALLINE QUARTZ DENKA F 90 DENKA FB 44 ... 

There are about 800 different types of glass in common use today. Figure 11.31 shows two-dimensional schematic representations of crystalline quartz and amorphous quartz glass. Table 11.5 shows the composition and properties of quartz, Pyrex, and soda-lime glass. 

SYNONYMS amorphous quartz, amorphous silica, cryptocrystalline quartz, fused quartz, fused silica, fuselex, microcrystalline quartz, quartz, glass, quartz sand, silicon dioxide, silicone dioxide, suprasil, vitreous silica. 

The capillaries used in CE have internal diameters of 20 to 100 p,m and outer diameters of about 400 p.m. They are typically between 10 and 100 cm long. The most popular material is fused silica, i.e. amorphous quartz, which is transparent to UV and visible light. These capillaries are externally coated with a polyimide layer of about 10 p.m thickness to increase fiexibility. For the detection window, this polyimide layer must be removed, by either scratching or burning it off. 

CAS 60676-86-0 EINECS/ELINCS 231-545-4 Synonyms Amorphous quartz Amorphous silica Cryptocrystalline quartz Fused quartz Fused silica... 

Tg and T are the temperatures of the transition onset and completion, respectively. The second scans were taken for all compositions to exclude the side endothermic effect of water desorption. The measurements were performed under nitrogen atmosphere at a heating rate of 20°C/min, over the temperature range from -20°C to 197°C, after cooling from 197°C to -20°C with the rate of 320°C/min. Amorphous quartz was used as the reference sample. 

Nishide T., S. Honda, M. Matsuura, Y. Ito, T. Takase (2000) Oriented and Non-Oriented Hf02-Y203 Films on Amorphous Quartz Glass Substrates Prepared by Sol-Gel Processes. Japanese Journal of Applied Physics, 39, L237-L240. 

Quartz is well permeable to helium. The selectivity of a pinhole-free, amorphous quartz membrane is very high for helium. Only hydrogen and neon show a significant permeation rate, but for this application this is negligible. In the enclosed volume behind the membrane the helium partial pressure rises to a pressure proportional to the partial pressure of the process side environment of the sensor. The total pressure of the external environment of the sensor system does not show any influence on the pressure inside the sensor volume. 

Figure 12.30 Two-dimensional representation of (a) crystalline quartz and (b) noncrystalline (amorphous) quartz glass. The small spheres represent silicon. In reality, the strucmre of quartz is three dimensional. Each Si atom is bonded in a tetrahedral arrangement to four O atoms.

The bridging of silica particles with the crystals of quartz, fluorite, periclase, bruscite, white asbestos, anthophyllite, and amorphous quartz (uncoated threads) was also studied. The specimens used in these studies were crystals with size 2x5x5 mm, which were mounted on the manipulator (Figure 1.28) and were cross-contacted with the silica-coated quartz thread. The area of contact was a plane with the dimensions 2x5 mm. The thread was positioned parallel to the short edge of the specimen. 

Figure 13 Reflectivity curves for deuterated polystyrene (390000 A/J adsorbed at an amorphous quartz surface from a 0.1% w/w cyclohexane solution [94]. The scattering length density of the solvent was adjusted (H/D ratio) to match the quartz so that the only signal arises from the adsorbed polymer. TIk curves for 1S ( ) and 3S (+) are shown the...

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