Subject sapphire

Finally, set beneath the Hall of the Holy Fire, is the Hall of the Sacred Ibis, the subjective Sephira of Hod. The altar is an unflawed crystal. The amber walls are topped by a domed ceiling of sapphire. The floor is of alternating tiles of ivory and gold. Eight pillars line the chamber, four of deep blue and four of milky marble, and the throne is of jasper. The tarot tapestries are those of Keys XII, XV, XVI, XIX, and XX. 

The shift of the A line in the epilayers has been connected with the variation of the lattice parameters of GaN [1,11,12], The shift of this line was also measured in samples subjected to hydrostatic pressure (see Datareview A3.1). Combination of all these data permits one to obtain the whole series of excitonic deformation potentials [6,16], Two sets of data are available which are consistent with each other and are given in TABLE 1. The discrepancies between them are linked to the differences in the values of the stiflhess coefficients of GaN used by the authors. Gil and Alemu [6] in their work subsequent to the work of Shan et al [16] used data not available when Shan et al calculated their values. The notations are the same and are linked to the relationship with the quasi cubic model of Pikus and Bir [17], Deformation potentials as and a6 have been obtained by Alemu et al [8] who studied the anisotropy of the optical response in the growth plane of GaN epilayers orthorhombically distorted by growth on A-plane sapphire. For a detailed presentation of the theoretical values of deformation potentials of GaN we refer the reader to Suzuki and Uenoyama [20] who took the old values of the stiflhess coefficients of GaN [21]. 

However, it can be seen in the work of Fatemi et al [26] that there is no clear correlation between the electrical properties and mosaicity of the GaN layers cm sapphire. To the authors knowledge, optical properties of GaN/sapphire layers are often worse for small tilt-mosaicity samples, but no comprehensive studies on this subject have been reported. 

GalnN quantum wells (QWs) sandwiched between GaN layers grown on sapphire or SiC are expected to be subject to these fundamental defects, too. Moreover, due to the rather large lattice mismatch between GaN and InN, the GalnN layer itself may contain new defects, when the critical thickness is exceeded. In addition, GaN and InN may be subject to a partial immiscibility and phase separation, which also produces defect structures. 

The surfaces of mtile Ti02 have been the subject of intense research because of their photo-catalytic properties for the dissociation of water. The hydroxylation rate on the surface and the kinetics of the reaction were shown to depend strongly on the surface stoichiometry and detailed atomic structure. In addition, like the two above surfaces of sapphire and magnesium oxide, rutile titanium dioxide surfaces stand as model metal oxide surfaces. Their atomic structure is thus of fundamental interest. 

Resistance. The pump should be inert to the various solvents, buffer salts and solutes to which it will be exposed in general use. In the vast majority of applications, stainless steel is used for metallic parts that contact the mobile phase, and this is perfectly acceptable. Elsewhere in the pump, resistant minerals such as sapphire or ruby are used for the pistons and in valve components subject to hard wear, and materials such as PTFE (Teflon ) are used for gaskets and seals. 

The anvil seats transmit a force to the anvil tables of the order of 10 kN. Thus the seats are subjected to a normal stress of some 2 GPa, for a 3 mm diameter table. This value may well be exceeded for ultrahigh-pressure work. Thus seats are most often made of tungsten carbide with an optical finish. In some X-ray measurements, beryllium seats have to be used, for their transparency. The mechanical performance is then drastically decreased, and the beryllium must be machined in specialized workshops. Single-crystal sapphire has been used, to provide an increased optical aperture. ... 

Miller et al. [35, 37] cleaned the sapphire and fluorite IREs by immersion in 0.1 M KOH solution and heating (40°C) and sonicating for 30 min. Next, the IREs were placed in a 50% (volume) mixture of chloroform and ethanol and simultaneously heated and sonicated for 10 min. Finally, the IREs were subjected to a low-temperature oxygen plasma for 30 min on each long face of the IRE and immediately placed in the ATR accessory. 

Espacer 300Z and resist solution 2EP-520A were spin coated at a thickness of 350 nm on a sapphire substrate to be subjected to electron-beam (EB) lithography. 

The portraits of Catherine Howard painted about 1521 show her wearing an oval gold pendant set with a sapphire, chased with the story of Tobit, and Princess Mary Tudor s inventory of 1542 lists brooches with the stories of the finding of Moses, Moses striking the rock, Susanna, Solomon, Abraham, David, Noah and Jacob s Dream, as well as subjects drawn from the New Testament. The only recognisably secular subjects in her pictorial jewels, indeed, are a brooch with the history of Pyramus and Thisbe and another with an Antike and a French motto. 

Near-resonant pump-probe lifetime measurements were performed by W. Schmid [105, 123], using the same picosecond dye laser system as for DFWM, described below. Th. Fehn further on investigated the subject in the off-resonant wavelength region between 720 nm and 820 nm, using a commercial Titan-Sapphire laser system (Coherent) with pulse lengths of ca. 120 fs, pumped by an argon ion laser (Coherent Mira). 

The results on the Pyrex, quartz, and sapphire surfaces were obtained after exposing each specimen to a drying temperature of 120°C for 10 minutes prior to subjecting it to the humid nitrogen atmosphere at 20°C. These conditions had originally been chosen to assure adequate removal of physically adsorbed water without causing excessive exposure of the surface to organic contamination. 

Figures 2.83 and 2.84 present spectra obtained with 2H-WS2 and IF-WS2 dispersed in PAO and subjected to a process of load and unload successively. The process of loading consists in recording the spectrum of the pristine product put on the ball, closing the contact and then applying loads from 1 to 10 N. The unloading corresponds to the opposite process. The diameter of the zone analysed inside the contact area is approximately of 5 am. After closing the contact, the appearance of a peak to 418 cm can be noticed. This peak is due to the sapphire flat and its intensity depends on focusing the beam during Raman spectrum acquisition. For the two samples, a displacement of this peak due to the pressure is observed, which shows an elastic deformation of sapphire during the test.

With an optical gap of about 9.9 eV, pure alumina is transparent in the visible and colorless domain. Like the electrical properties, the colored effects depend primarily on the impurities. Sapphire and raby have been the subject of numerous studies [BUR 84] and it is esthetically and scientifically interesting to mention the alexandrite effect (from the name of a chrysobeiyl (Al2Be04) containing a little Cr +) which is green in daylight and red if illnminated by an incandescent lamp [NAS 83]. 

First of all, a laser source able to produce short pulses with high energy is required. Presently there are a large variety of ultrafast laser systems available on the market. Substantially all these laser systems are based on the Ti sapphire solid state active medium and on the Kerr lens mode-locking principle. There is a large amount of literature on this subject [69] and we will recall here only the principal features of our present laser system. This is composed of a Kerr lens mode-locked Ti sapphire oscillator and a chirped pulse amplification system [19,70], see Fig. 2.2. The oscillator source is a Kerr-lens mode-locked Ti sapphire laser (FemtoRose lOMDC, by R D Ultrafast Laser) pumped by... 

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