Flat windows

The cells in which the scattering solutions are measured should have flat windows at the... 

An alternative type of cell, which consists of two parts of optically flat windows, is suitable for CD and MCD measurements of small-volume samples. One of the window affords a trough for filling in the sample. Otherwise, a well-calibrated spacer is inserted to a conventional cell for adjusting its path length. The light path length is calibrated by using the absorbance of an appropriately diluted solution of benzene or toluene. 

Aqueous suspensions (ca. 50 mg of sample) were irradiated with a 200W Osram HBO bulb with a total energy output at the flat window of the flask of 470 mW/cm2. Analysis of H2 and 02 evolved into the flask free volume (ca. 17.6 cm3) was made by GC using a molecular sieve 5 A column and Ar as carrier gas. Detection limit was 1 pmo 1 for 02 and 0.1 pmo 1 for HL in that volume. 

B) orientation of crystals (e.g., on flat window), formation of glossy sections, reflected light contains regular and diffuse contributions. 

Kawai et al. (2006) extended the design of a high-pressure cell to accommodate operating conditions of 50 bar and 723 K. The cell had low volume, with flat windows that were chemically, structurally, and thermally stable, fabricated from a novel material, cubic boron nitride, which was synthesized by the authors by sintering hexagonal boron... 

A CW tunable dye laser (Stilbene 3) is pumped by the ultraviolet lines of an argon ion laser. The laser is focused in a cell filled with a mixture of cesium and hydrogen. The cell (10 cm long with an inside radius of 2.6 cm) is connected to a reservoir containing liquid cesium and to a pumping system or a hydrogen gas tank. It is placed in an oven heated independently from the reservoir. The laser beam enters the cell from below through a flat window and is focused at a point 1 cm above the window. 

This result could explain differences in spectral data in the same systems obtained with low incidence angles (flat window) and high incidence angles (prismatic or spherical windows). The latter can furnish almost featureless spectra for solution species with s-polarized light (compare the curves in Fig. 12 at rf = 1 pm) and induce the wrong conclusion that no solution feature interferes in the spectra measured with p-polarized radiation [35-37]. On the contrary, the use of a flat window leads to comparable intensities for s- and p-polarized radiation spectra [27,38]. 

Reactions were carried out under vacuum in silica cells incorporating an optically flat window through which the polymer film could be irradiated. The film, supported on a silica disc, was placed on the bottom of the cell which was placed in a furnace controlled at M.5°. The temperature of the film was measured by a Chromel-Alumel thermocouple placed inside the reaction cell in contact with the film. 

Detonation velocities in confined charges may be measured with a streak camera or by pin switches. The techniques are potentially accurate to 0.5%. The camera has the advantage that a continuous record of buildup and detonation transfer can be obtained [18,19], In the sample holder (Figure 8), the central hole has the diameter of a typical detonator. 0.136 in. (0.345 cm), and the initiation of the lead azide is by a hot wire. The flat window, cut and polished from a 3/8-in. (0.095-cm) -diam rod, which covers the slit provides a bright, sharp slit image through which to view the propagation of detonation with the camera. 

Consider two closely located parallel flat plates having temperatures Ti, 7i and emissivities < i, 2- Place between these plates (a) a third flat plate with emissivity eo> (b) a flat window screen, j being the total hole area relative to the apparent surface area. Determine the reduction in the radiation heat transfer between the plates. 

Fig. 3.21 A Poulter-type window on an unsupported-area Bridgman optical plug, used for window testing (a) window, (b) flat window seat, (c) hard-steel plug, (f) washer packing, (g and h) bevels on the outside of the plug and the window, (i) a bevel on the inside diameter of plug and, (j) a retaining brass cap d and D are the inner and outer diameters of the window seat e is the thickness of the window (from reference 16).

Instrumentation. Because water is a weak Raman scatterer (for a review of vibrations of water molecules adsorbed on a SERS-active metal surface, see [421]) and most other electrolyte solution constituents are present only in small concentrations, standard eells with the working electrode surface close to a flat window are suitable no thin layer arrangement is required. This results in good electrode potential control and current distribution. A typical design is depicted in Fig. 5.64 for further examples and details of both the electrochemical and the spectrometric setup, see also [372]. 

Electrochemical SFG is typically conducted in thin-layer spectroscopy cells similar to those used in infrared spectroscopy. A large angle of incidence will enhance the intensity of the light fields at the surface and therefore increase the signal, as shown in Fig. 5.5 for visible Hght. The light beams enter and exit the cell through a flat window, prism, or hemispherical window. The windows... 

For studies of laser action in organic semiconductors polymer films with uniform thickness, d, ranging from 0.5 to 4 p.m were slowly spin-coated from fi-esh chloroform solutions onto quartz substrates. The variation in d was typically less than 5% over the film length of 1 mm [96]. For polymers in solutions we thoroughly mixed the polymer powder in good solvents such as THF or chlorophorm typically with concentration of few milligram per milliliter. Then the polymer solution was placed in a transparent cuvette with flat windows, in which the side windows were tiled to avoid optical feedback. 

The experimental facility and instrumentation are shown in Fig. 1. The flow facility consists of a vertical 2.5 cm diameter, 15 cm long Pyrex glass test cell mounted beneath a low-pressure reservoir of volume 0.27 m. The test cell is sealed by an aluminum foil diaphragm, which is ruptured by pneumatically driven knife blades. The test cell is surrounded by a liquid-filled jacket with flat windows. This serves two purposes to eliminate the cylindrical lens effect of the test liquid (by choosing a jacket liquid with a refractive index similar to that of the test liquid) and to provide temperature control (by circulating the jacket liquid through a heat exchanger). 

Though the internal reflection mode (ATR) encounters many applications, the external reflection mode is much more versatile to study metallic electrode surfaces. The external reflection mode has been introduced to study metallic electrode surfaces by Bewick and coworkers [10]. To minimize the strong attenuation of the radiation by the presence of a solvent in electrochemical systems, the electrode was placed very close to the infrared transparent window. Practically, the electrode is slightly pressed against the flat window surface leaving a very thin electrolyte layer between the electrode and the window. 

An important detail is the difference between the reflectivity using a flat window or a prismatic window for the in situ spectra. Simulating a change in absorbance in the thin-fllm layer, that is, a change in the solution composition, data of reflectivity are shown in Fig. 11 (a, b)... 

Fig.n Si mulated change in reflectivity for the system (a) flat window/electrolyte/metal for a change in the absorption in the electrolyte layer (note the interference fringes caused by the internal reflections) and (b) prismatic window/electrolyte/metal. The parameters used in the simulation are n- =1.0 (air) n2 =. 4 (Cap2 window) /13 = 1.32 + i0.015 (electrolyte) and n4 = 10.9 + 15.6 (Pt). Electrolyte film thickness 2.0 x 10 m flat window thickness ... 

Precision work is carried out with reactors like that shown in Figure 3.7. These reactors can be machined from Lucite or Plexiglas. The reactors are relatively small (about 30 mL) in order to reduce the quantity of reagents consumed. If spectrophotometric detection is to be used, then it is necessary either to build the reactor from an optically transparent material like quartz, or, more economically, to build in a pair of transparent (and flat) windows for the light path of the spectrophotometer. 

Flat window screening, at least 1 foot (30 cm) square... 

Flat windows of the cell should be placed perpendicular to the beam of light in order to avoid light reflection. 

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