Two-window high pressure cell

FIGURE 7.2 Schematic view of a two-window high-pressure cell to accommodate the pillbox optical cell for pressures up to 200 MPa (1) pressure plug (2) O-ring (3) reaction compartment (4) a A- and O-ring (5)sapphire window and (6) the pressure connection. 

Figure 5. Schematic view of a two-window high-pressure cell [21] 1 is a pressure plug 2 is an O-ring 3 is the reaction compartment 4 is a A- and an O-ring 5 is a sapphire window 6 is the pressure connection.

Fig. 1.3. Schematic view of a two-window high-pressure cell ...

High pressure cell, two-window, 13 418 High pressure chemistry, 13 402-455 apparatus, techniques, and methods in, 13 410—436... 

A schematic representation of the experimental apparatus is shown in Figure 1. A cylindrical high pressure cell (6) with 30 ml volume was built with two sapphire windows with an optical width of 18 mm mounted in the central axis. To produce pendant drops, a narrow capillary was screwed vertically into the cell. The tip of the capillary could easily be replaced with tips of other sizes. The main components of the circulation equipment are a stirring autoclave (1) of 600 ml volume and a high pressure gear pump (2) to circulate the liquid or the supercritical gas phase depending on the position of the valves. 

Fig. 4.7 An optical high-pressure cell with an internal cell that consists of (1) a PTFE tube, (2) two CaF2 windows, and (3) the sample volume.

Luminescence appears in mechanistic chemistry in two distinct contexts. The details of the emission process itself are important in photochemistry, which is considered in Section 8. In other applications, fluorescence is simply an assay for qualitative and quantitative analyses. Good selectivity and sensitivity have earned it a role in commercial apparatus. However, the sensitivity is compromised by the small windows of a high-pressure cell, which limit the solid angle available. Laser sources help, but they restrict luminescence methods to specialized facilities. It is important to understand the polarization artefacts which may be introduced by thick windows and to appreciate that they may change with pressure. Many optical elements, including monochromators, have transmission properties that depend on the polarization. 

Very recently, Addleman et al. described a high-pressure cell for the study of TRLIF of uranyl complexes in supercritical CO2 (21). A schematic of the optical cell is shown in Figure 3. The cell has two perpendicular optical paths that are both orthogonal to the SCF flow, allowing absorption, fluorescence, and Raman measurements. The cell body was machined from stainless steel with an internal volume of 0.3 ml. The cell windows were made of 2-mm-thick synthetic... 

Fig. 3. Schematic drawing of the high pressure electron spectrometer. A, Argon ion gun D, differentially pumped region EL, electron lens G, gas cell HSEA, hemispherical electron analyzer LO, two-grid LEED optics LV, leak valve M, long travel rotatable manipulator P, pirani gauge S, sample TSP titanium sublimation pump W, window X, twin anode x-ray source.

HP IR transmission cells can be divided into two broad categories, namely (i) where the contents of the high pressure vessel are observed directly through IR transparent windows and (ii) where the reaction solution is circulated from the autoclave to an auxiliary observation cell. The first type is exemplified by the cell shown in Figure 3.2, developed by Whyman at ICI [2, 3]. The stirred reaction solution surrounds the cell windows in an arrangement that minimises the problem of... 

Bare et al. (2006) described two cell designs, one for transmission XAFS and one for fluorescence measurements, whereby all of the critical components could be purchased commercially, with little machining required. The designs are simple, robust, and relatively low in cost. The basis of the designs is a quartz tube with windows fabricated from an appropriate material. The tube is heated by a clamshell furnace. The catalyst powder (with or without diluent) is hand-pressed into a quartz sample holder that is inserted into the quartz tube. Thus, a spectroscopically uniform sample is obtained without the high pressure compaction that is necessary to obtain a self-supporting wafer. The cell has been operated at temperatures from 80 to 1373 K, but the maximum working pressure is only approximately 1 bar. 

The high-pressure optical cell is comprised of a Monel 400 body, gold or teflon O-rings, and CaF2 or sapphire windows. The two windows are secured using an opposed force-type seal incorporating Belleville spring washers. The cell is essentially leak-free at pressures up to 3000 psia ( -200 atm). 

Fig. 6.7-4 shows an optical cell for absorption studies up to 3500 bar and 300 °C. The two windows (1) are sealed according to the principle illustrated in Fig. 6.7-3. The steel plugs (5) are pressed against the body of the stainless steel cell by a flange (3) which is secured by several screws (2) on each side. The optical path length is determined by the distance between the internal surfaces of the high-pressure windows. Holes are drilled...

Figure 11 The diamond-anvil cell has emerged as the dominant and most versatile tool for achieving high pressures (up to millions times of the atmospheric pressure). It uses two diamond anvils, which exert pressure and serve as windows on the sample. A metal gasket confines the sample and supports the anvils. Because diamond is the strongest material known and is transparent over a wide range of the electromagnetic spectrum, various high-pressure experiments are performed using synchrotron radiation...

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