Optical cells cylindrical

Kimura and Miller [29] demonstrated (Table 13.7) that mercury in several organic forms can be digested and aerated from unfiltered soil digests. For samples of lOg of soil cores containing 5pg mercury or less, the standard deviations of a single determination were 0.12, 0.15 and 0.23pg, respectively, using 2cm cylindrical optical cells. 

The solution was contained in a cylindrical Pyrex or silica optical cell, 2.5 cm. in diameter and 2 cm. optical depth, fitted with a side arm of diameter about 1 cm. for connection to the vacuum line (see Fig. 10). Both phosphorescence and delayed fluorescence in fluid solution at room temperature are quenched by exceedingly low concentrations of molecular oxygen, and efficient deaeration is of the utmost importance. The following procedure was found to be satisfactory. The cell was first cooled in an acetone/C02 bath and pumped out. It was then isolated from the pump, refluxed to remove dissolved gas, cooled again in the... 

Fig. 22. Sensitized delayed fluorescence spectra of anthracene in 10 SM phenan-threne solution.38 Intensity of exciting light was approximately 2.7 X 10-8 einstein cm. 2 sec. 1 at 3.19m-1 (313 dim)- Delayed emission spectra with anthracene concentrations of (1) 10 8Af, (2) 5 X 10 W, (3) 10-W, (4) 10- M, (5) 10 9M. Curve (6) Fluorescence emission spectrum of solution 1 at 260 times less sensitivity. (Owing to variation in the shapes of the cylindrical optical cells, the relative intensities of the delayed emission are only approximately proportional to 9A/fF.)...

Two types of Raman optical cells have been used so far. Fused silica in the form of cylindrical tubes of inner diameter 2-10 mm are the proper and simplest material for non-corrosive melts. Windowless cells made of graphite or noble metals have proved adequate for studying corrosive fluoride and/or oxide melts. 

Fig. 6.5 Some typical sample cells, (a) Various types of optical cell, (b) A completely sealed optical cell, (c) An exploded view of a high-pressure conductivity cell (A) the plug of the high-pressure cell, (B) a hollow cylindrical Kel-F screw, (C) a Teflon cone, (D) a platinum wire lead, (E) a platinum electrode, (F) a Kel-F body, (G) a Viton O-ring, (H) a flexible Teflon tube, (I) a Teflon screw, (J) an aluminium holder, and (K) a steel cone, (d) An inverted pillbox cell for infrared spectroscopy.

Fig. 11. Electro-optical cell W, working electrode R, reference electrode C, counter electrode a. Teflon holder fr, cylindrical quartz cell c. Teflon lid d, Luggin capillary e, compartment for counter electrode /, compartment for reference electrode g, sample inlet h, screw hole i, gas inlet /, gas outlet. (From Kusu and Takamura, 1985b, with permission.)...

Figure 5.26 Cells for liquid samples, showing just a few of the wide variety of types and sizes available. From left to right, top row standard 1 cm spectrophotometer cuvet with two optical faces and two frosted faces semimicro 0.7 mL cuvet 10 p,L submicro cell constant temperature cell with a jacket for circulating a temperature-controlling fluid. From left to right, bottom row 5 mm fluorometer cuvet (all four faces are optically clear) in-line continuous flow cell for process monitoring (sample flow is from bottom to top) 10 mm flow cell cylindrical cell. [Courtesy of Starna Cells, Inc., Atascadero, CA (www.starna.com).]...

Hence c(g/ml) is the concentration of colloidal suspension G90 is the reading on the LS photometer at 6 = 90°, 2 is the path length, which equals the cell diameter when using a cylindrical cell t is the turbidity obtained from measurements of optical density. Table 4 gives the results of calibrating a Sofica instrument with colloidal... 

Figure 6. Instrumental schematic for vacuum UV photofragmentation-laser induced fluorescence measurement of ammonia SHGC, second harmonic generation crystal SFMC, sum frequency mixing crystal BS, beam splitter BD, beam dump TP, turning prism CL, cylindrical lens R, reflector TD, trigger diode OSC, oscillator cell AMP, amplifier cell BE, beam expander G, grating OC, output coupler M, mirror BC, beam combiner L, lens A, aperture PD, photodiode SC, sample cell RC, reference cell FP, filter pack SAM.PMT, sample cell photomultiplier REF.PMT, reference cell photomultiplier PP, additional photomultiplier port EX, exhaust and CGI, calibration gas inlet to flow line. (Reproduced with permission from reference 15. Copyright 1990 Optical Society of America.)...

Cautionl The following spectrophotometric analysis shovM he performed in a hood. To determine the concentration of diazomethane in the ether solution obtained in this preparation, a 5-ml. aliquot of the distilled solution is diluted to 25 ml. with ether, and a portion of this solution is placed in a cylindrical Pyrex cell with an internal diameter of 1.0 cm. The optical density of the solution is determined at 410 m/i with... 

Cylindrical cells are easier to construct and thermostat than flat cells and dark-field illumination can be obtained by the ultramicro-scopic method of illuminating the sample perpendicular to the direction of observation (see page 52 and Figure 7.6). The volume of dispersion required is usually less for cylindrical cells than for flat cells and, owing to the relatively small cross-section, it is more often possible to use platinum black rather than reversible electrodes with cylindrical cells. However, unless the capillary wall is extremely thin, an optical correction must be made with cylindrical cells to allow for the focusing action of the tube, and optical distortion may prevent measurements from being made at the far stationary level. Cylindrical cells are unsatisfactory if any sedimentation takes place during the... 

FIGURE 6.3 Absorption of light of a highly divergent beam by a substance placed in a cylindrical cell. Although the effect of reflection on the window has not been considered here, it can be introduced by a simple application of the laws of geometrical optics. 

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