Quartz disk

The result was that only a small fraction (10-6) of the spores which had been subjected to space conditions without protection survived. The same was true for those which were protected by a quartz disk or covered by a thin layer of clay. However, the survival rate of the spores mixed with the protective materials listed above was about five orders of magnitude higher, while almost 100% of those in the small cube survived (Horneck et al., 2002a). This experiment suggests that small pieces of rock, only a few centimetres in diameter, could act as a transport medium between certain heavenly bodies. However, the classical panspermia hypothesis, involving seeds of life on grains of dust, must be completely unreal. 

The PMMA-Phe synthesis, characterization, film preparation, apparatus and experimental scheme are described elsewhere (H) Briefly, the PMMA chains, copolymerized from MMA and Phe-labelled monomers, were characterized via gel permeation chromatography (GPC) M = 411,000, M = 197,000 and M M - 2.08. UV-absoifption measurementsnindicated that ca. I % of all monomer units were Phe-labelled. The sample was dissolved in toluene and was spin-coated onto 1-inch diameter quartz disks. Then, the films (ca. 1 /zm thick) were annealed at 160 C for 60 minutes under vacuum. 

Figure 11.8 Cell for use of thin-film electrodes. A, Aluminum retaining plate B, OTE C, copper foil D, O-ring E, Lucite body F, glass salt bridge for reference electrode G, Hamilton valves H, auxiliary electrode I, quartz disk. [From Ref. 89, with permission. Copyright 1972 American Chemical Society.]...

We intend to examine the problem of the mask in the spinning rotor. We also intend to construct a quartz disk with lines that are arcs about the center of the rotor. Placed in a special holder at a plane equivalent to the mid-plane in a normal cell, it would provide radial magnification and correction information for any experiment. 

If the electrodes on both sides of the quartz disk are connected to an oscillator circuit, frequencies / can be measured with a frequency counter. The changes of superficial mass can be calculated from changes of the frequency A/ using the Sauerbrey-equation (-> quartz crystal microbalance). Changes at the sensitivity level of 0.1 Hz at a fundamental frequency of 10 MHz correspond to a mass of about 0.4 ng cm-2. 

There are no clear design rules regarding the ratio of the diameter of the electrodes to the thickness of the substrate, but the static capacitance of the quartz disk can be held constant by scaling the RF electrode diameter in proportion to... 

Solid state spectra from thin films on quartz disks are relatively easy to measure at all temperatures but the spectral data are complicated by the broadening that arises due to the Davydov effect. While this enables spectra to be recorded over a wavelength range down to 200 nm, the spectral envelopes are not at all similar to the spectral bands observed in either the vapor or solution phases. An alternative technique that mixes the matrix isolation and thin film advantages is to dissolve the solute into polymers. The subsequent cast film may allow distortion-free and solvent-reduced spectral measurements at a range of temperatures. 

The quartz disk is used as the bottom plate of a cell culture vessel and is moimted in a temperature controlled crystal holder (37 °C). The surface electrodes on either side of the quartz are connected to an impedance analyzer (Solatron Instruments, SI-1260) operating in continuous wave mode. The frequency-dependent complex impedance Z(J) returned by the impedance analyzer is expressed as magnitude of impedance Z (f) and phase shift between voltage and current (f). The raw data is analyzed by the well-known Butterworth-Van Dyke (BVD) equivalent circuit with the liunped impedance elements Co, Rq, iq, Cq and Zl. Rq, Lq and Cq represent the piezoelectric properties of the unperturbed resonator itself, whereas Co summarizes its dielectric properties and all parasitic contributions arising from contacts and wiring. The load material in contact with the resonator surface is represented by the complex impedance Zl. As long as the resonator is not loaded too... 

Solomon and Caton (S12) described a recording colorimeter. Absorption cells according to Lowry and Bessey are used. Six of these cells (four samples of 30 pi, one standard, and one blank) are placed in a special carriage, which ensures that the position of each cuvette be reproducible within 0.1 mm. An accuracy of 1% at optical density in the 0.1 region and of 0.2% in the 0.4 region is claimed at a wavelength of 476 mp. Six samples can be measured and recorded in less than 200 seconds. In our opinion this instrument is not to be recommended for routine work because of the use of six absorption cells instead of one stationary cell. The same remark applies to colorimeters or spectrophotometers which use capillary absorption cells closed by glass or quartz disks. However, capillary absorption cells are indispensable when only very small volumes are available. 

A rather simple microspectrophotometer which permits accurate absorption measurements using a capillary cell with a content of only 10 pi was described by Wallach and Surgenor (Wl). The cells are made from borosilicate glass tubing of 1-mm bore. They are precisely 10 mm long and are closed by quartz disks. These are held in position by capillary forces. A monochromatic light beam 0.4 mm in diameter is obtained from a glass prism monochromator. The cell is positioned... 

Two types of evaporative flame ionization detectors (FID) are the moving wire (100,101) and the rotating disk detectors (102-104). These convey the eluant along a wire or quartz disk into an evaporation chamber, where the volatile carrier solvent is removed. The nonvolatile sample is then passed through an FID. Any unbumed sample is removed in an ashing chamber before the wire or disk returns to its eluant-collecting position. 

Experiments in Photoresist Films. Quartz disk wafers (1 inch in diameter) were cleaned, using a protocal that involved soaking them in 30 % H202/conc. H2SO4 for 15 minutes, followed by a 2 minute soak in 10 % HNO3, followed by a 2 minute soak in CHaOH/conc. HCl, followed by a 2 minute soak in cone. H2SO4. Finally, the wafers were rinsed in de-ionized water for 5 minutes (3x) and then dried in an oven at 120 °C overnight. 

Photoresist formulations comprising 20 wt % of polymer, 3-10 wt % of PAG (relative to total polymer weight) in PGMEA were spin coated at 2000 RPM on 1 inch quartz disks. The resulting films were baked at 150 °C for 60 seconds. Typical film thickness was 1 pm. The films were then exposed to 193 nm radiation using an ISI ArF Stepper. Following this, the exposed films were dissolved off the disc with THF and titrated against 2 mL of a solution of ACRAM. The photoresist polymers studied included poly(CBN-a/f-MAH) and poly(CBN-co-NBCA). 

Figure 3 Principle of construction of atomic absorption spectrometers. (A) Single-beam spectrometer with electrically modulated lamp radiation (B) double-beam spectrometer with reflection and splitting of the primary radiation by a rotating, partially mirrored quartz disk (chopper). 1 - radiation source, 2 -sample cell (atomizer), 3 - monochromator, 4 - detector, 5 -electronics and readout (by permission of Wiley-VCH from Welz B and Sperling M (1999) Atomic Absorption Spectrometry, 3rd, completely revised edition. Weinheim Wiley-VCH).

A similar method for evaluating the adhesion of mutually perpendicular fibers (glass, quartz, or metal) with diameters from 0.2 to 1.2 mm was used by G. I. Fuks [96]. He also described an instrument (Fig. III.14) in which the forces of interaction between colloidal particles could be determined by a method involving plane-parallel disks (disk diameter 5-20 mm). The basic part of this instrument consists of the steel or quartz disks 1 and 2 immersed in the test liquid 3. The distance between the disks is measured in terms of the capacitance of the plane-parallel condenser including the disk 2. The lower limit of sensitivity of this method is 0.022-0.025 /mi in this case, the relative error is 12-18%. 

A schematic of the working electrode configuration is shown in Fig. 12. The radius of the quartz disk, Tq, is 1/2 inch the thickness, dq, is 1/8 inch. A thin layer of titanium ( 5 x 10 cm) is vapor deposited on the quartz disk followed by deposition of the desired thickness, of gold (generally 10 cm where noted 0.3 x 10 " cm). The radius of the deposited gold layer, r, is 1.1 cm the radius of the exposed electrode, /- , is 0.475 cm. Details of the preparation of the gold electrode are presented in Sec. V.B. The entire assembly is held together with a simple clamp (not shown in Fig. 12). 

The wet disks are immediately immersed into the vapor of refluxing isopropanol. Once they reach the reflux temperature, as noted by a reduction in the rate of alcohol condensation on the disks, they are removed into the room air where they rapidly become dry and slowly cool to room temperature. At this point, the disks are individually weighed to the nearest 0.1 mg. The disks are then loaded into a metal tray with large circular regions on their bottom faces exposed and the tray placed in the load lock of a vacuum chamber. The load lock is pumped to about 10 torr and then the tray is translated into the chamber and the load lock sealed off from the chamber. The chamber is pumped to about 10 torr with a cryopump. The major residual gas is water from the rotatable rubber seal used between the evacuated space in the chamber and the water flow path into and out of the rotatable copper crucible mentioned below. Titanium vapor is sublimed from a Ti ingot by bombardment with about 8 keV electrons while the periphery of the ingot is cooled by sparse physical contacts with the water-cooled copper crucible in which it rests. The Ti vapor condenses in the line of sight from the source onto the exposed bottoms of the disks. The thickness of the deposited titanium, is monitored by a calibrated quartz crystal balance close to the quartz disks. Typically (iji 5 x 10 cm. 

Referring to the right-hand side of an equation or portion of an equation Radius of vapor deposited gold layer on quartz disk Fraction of light reflected from electrode surface... 

Radius of quartz disk supporting the working electrode... 

If pathlengths of 0.1 mm or less are required, it is probably best to use demountable cuvettes where the sample is dropped onto a quartz disc that is etched to a predefined depth and then another quartz disk is carefully placed on top. In this case sample recovery is very difficult, so the smaller volume of cylindrical cells makes them more attractive than rectangular ones. A simple cuvette holder for demormtable cylindrical UV cells may be created from an infrared cell holder and pieces of rubber (a mouse mat proves ideal) with holes drilled at the appropriate places to allow the holder assembly screws to pass through (Rgure 4). Any such cell holder must be located perpendicular to the light beam... 

---