Quartz optical properties

Chemical properties of deposited monolayers have been studied in various ways. The degree of ionization of a substituted coumarin film deposited on quartz was determined as a function of the pH of a solution in contact with the film, from which comparison with Gouy-Chapman theory (see Section V-2) could be made [151]. Several studies have been made of the UV-induced polymerization of monolayers (as well as of multilayers) of diacetylene amphiphiles (see Refs. 168, 169). Excitation energy transfer has been observed in a mixed monolayer of donor and acceptor molecules in stearic acid [170]. Electrical properties have been of interest, particularly the possibility that a suitably asymmetric film might be a unidirectional conductor, that is, a rectifier (see Refs. 171, 172). Optical properties of interest include the ability to make planar optical waveguides of thick LB films [173, 174]. 

Chang EK, Rohlfing M, Louie SG (2000) Excitons and optical properties of alpha-quartz. Phys Rev Lett 85 2613... 

Several gemstone species occur in various colors, depending on the presence of impurities or irradiation-induced color centers. Examples are the beryl, corundum, and quartz families. Quartz has poor optical properties (RI = 1.55, DISP = 0.013), but becomes of gemological interest when it exhibits attractive colors. Any material can have its color modified by the addition of various impurities synthetic mby, sapphires, and spind are produced commercially in over 100 colors (2). Synthetic cubic zirconia has been made in essentially all colors of the spectrum (11), but only the colorless diamond imitation is produced commercially in any quantity. 

Pt acts like a neutral density filter through a wide wavelength range and can be used in the UV when the film is on quartz. Au has an optical window with maximum transmission at 540 nm. On quartz, Au can also be used in the UV when the conductivity is comparable to Pt. For the visible region, Au films with good transmission and with resistance as low as a few ohms per square can be prepared. Typical optical properties are shown in Figure 11.3 [55]. The electrochemical properties are similar to bulk Pt and Au, as seen in Figure 11.5 [74],... 

A new view on this problem arose after the diamagnetic centers with two-coordinate silicon atom were observed at the surface of mechanically activated silica [70]. The subsequent studies of the optical properties of these centers [71] have shown that they are close to those centers that were observed earlier in the bulk of quartz glass but referred to the oxygen vacancies. It has become evident that, apart from the combination reaction of two radicals (=Si-0)3Si and (=Si-0)3Si resulting in the oxygen vacancy, an alternative reaction of their disproportionation with the formation of a center containing two-coordinate silicon and the restoration of one of the siloxane bonds is possible ... 

The optical properties of quartz cranked into Lifshitz s formula, for plane-parallel surfaces but modified by the Derjaguin transform for a sphere and a flat, gave an attraction that fit neatly with experiments. 

The structures were grown in an ultra high vacuum (UHV) chamber VARIAN with a base pressure of 2-10 °Torr equipped with differential reflectance spectroscopy (DRS) [3] for a study of optical properties of the samples. Samples were cut from n-type 0.3 D cm Si(l 11) substrates. The silicon was cleaned by flashes at 1250 °C (7 times). Surface purity was controlled by AES. RDE was carried out at 500 °C, 550 °C, and 600 °C. The Cr deposition rate was about 0.04 nm/min controlled by a quartz sensor. An additional annealing during 2 min at 700 °C was done for all samples before the growth of silicon epitaxial cap layer. 

The measured enthalpies of adsorption of alkanes into zeolites are very large, and can be calculated from this formula [13]. The dielectric constants for the open networks formed by the aluminium silicate frameworks of zeolites can be related to the known and measured dielectric and optical properties of bulk quartz. The calculation assiunes that the zeolite framework tessellates a hyperbolic surface as described in Chapter 2. The polarisabilities of different adsorbate alkanes are also known. When the calculations are carried out for a whole range of alkanes as adsorbate molecules and for different zeolites (with differing pore structure and size) the agreement between measured and predicted heats of adsorption is excellent (cf. Fig. 3.2). The results depend... 

Measuring cuvettes, in which sample solutions are placed, are made of various materials depending on the range of radiation used in the measurement. Measurements in the UV are performed with the use of quartz cuvettes. Synthetic quartz, which is less contaminated with traces of metals, has better optical properties. Measurements in the VIS range are made using quartz, glass, or plastic cuvettes. 

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