Optical cells design

Further sensitivity enhancements of PDA are likely to stem from advanced flow-cell design using fiber-optic technology to extend the... 

One other difference lies in the type of detection technique used, which dictates the flow-cell design. Thus, a distinction can be made in this respect between optical (absorptiometric, luminemetric) sensors, which make measurements of the bulk solution where the flow-cell is immersed, and electroanalytical (amperometric, potentiometric) sensors, where measurements are based on phenomena occurring at the electrode-solution interface. 

Optical cells can be designed for very high pressure of 1000 MPa and, more and temperatures from -273 to 800°C. 

Figure 17.11 Transmission spectroelectrochemistry cell designed for use with room-temperature haloaluminate melts and other moisture-reactive, corrosive liquids, (a) Auxiliary electrode and reference electrode compartments, (b) quartz cuvette containing the RVC-OTE, (c) brass clamping screw, (d) passageway between the separator and OTE compartment, (e) fritted glass separator, (f) A1 plate, (g) lower cell body (Teflon), (h) upper cell body (Teflon). This cell is normally used inside a glove box and is optically accessed with fiber optic waveguides. [From E. H. Ward and C. L. Hussey, Anal. Chem. 59 213 (1987), with permission.]...

Optical materials and various infrared cell designs. 

The Waters Assoc. R401 differential refractometer is based on an optical-deflection design rather than on light reflection. This permits the use of a single cell throughout the refractive-index range of 1.00-1.75. The system also has a wider dynamic range of linearity for quantitation than the Fresnel-type refractometers. 

In order to delineate the origin and development of flooding with high spatial and temporal resolution in PEM fuel cell, recent research has resorted to the transparent cell design based on optical diagnostics. 

Raman spectroscopy is characterized by lower sensitivity than IR spectroscopy, but in contrast to IR spectroscopy, Raman spectroscopy may be used to investigate catalysts under supercritical conditions of C02 or H20, because there are no strong absorptions by these molecules that interfere with the absorptions by the catalyst as is the case in IR spectroscopy. Griinwaldt et al. (2003) reviewed cell designs for spectroscopic experiments under supercritical conditions that either feature a window (lens) to focus the laser beam inside the cell, or fiber optics that are directly inserted into the cell (Howdle et al., 1994 Poliakoff et al., 1995). In some cases, several techniques may be combined (Addleman et al., 1998 Hoffmann et al., 2000). Such cells are designed with minimal void volume so that reliable kinetics and time-resolved analyses can be performed. 

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