Cells for liquid samples

Sample cells include Lindemann/capillary tubes (normally 1 mm in diameter) and aluminium holders. In the latter, thin aluminium windows sandwich the sample in a cylindrical aluminium sample holder. The diffraction from the aluminium is observed in this case, and may be used as a calibration standard. For low-temperature materials, the aluminium window can be replaced by the polymer Kapton. Beryllium may also be used [14]. Sample volumes of between 50 and 100 pL are typically required. 

Binary mixtures that melt close to room temperature, namely AlCl3/N-butylpyri-dinium chloride mixtures, have also been investigated. Takahashi et al. [17] have also shown that for the 1 1 composition, [AlClJ predominates with a tetrahedral environment. At a ratio of 2 1, [Al2Cl7] becomes the main species. At high temperature (above 150 °C), some decomposition to [AlClJ and Al2Cl(3 was observed. 

Many of the systems studied are based on [MClJ anion. Neve et al. have extensively studied the formation of liquid-crystalline phases of N-allcylpyridinium salts with allcyl chain lengths of n = 12-18 with tetrahalometalate anions based upon Pd(II) [22] and Cu(II) [23]. In general, the liquid-crystalline phases exhibit lamellar- 

Similar lamellar structures are formed for l-alkyl-3-methylimida2olium cations with [PdCl4] when n 12. As with the pyridinium systems, mesomorphic liquid crystal structures based on the smectic A structure are formed [24]. 

Similarly, N-allcylammonium [28] and alkylphosphonium [29] salts form lamellar phases with smectic bilayer structures. In both cases. X-ray scattering also showed the isotropic liquid not to be completely disordered and still displaying similar features to the mesophase. Buscio et al. [28] showed that in N-allcylammonium chlorides the feature was not only much broader than that observed in the mesophase but increased in width with decreasing chain length. 

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What are the differences between a sealed cell, a demountable cell, and a sealed demountable cell for liquid sampling ... 

Fig. 7 Diagram of a circular demountable cell and a circular sealed cell for liquid samples. (From Perkin-Elmer Corporation.)...

Figure 4.19 (a) Standard demountable cell for liquid samples, shown in an exploded view. The... 

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).]...

Figure 8.27 Cells for liquid samples, loose powders and chips, (a) Two types of disposable polyethylene sample cups for liquids and loose samples, consisting of a cup and snap-ring to hold the polymer film cover. The cells with polymer film in place are shown at the top of the photograph. The disassembled cup and ring pieces are shown at the bottom of the photograph. [Courtesy of SPEX Certiprep, Inc. Metuchen, NJ (www.spexcsp.com).] (b) Liquid and other loose samples in cells such as those shown in the photo, and then inserted into a sample cassette of the type shown in Fig. 8.26(a) for a face-down configuration spectrometer. As shown, dust sampled on impact filters or thin layer samples may be inserted directly into the sample cassette. [Courtesy of Thermo ARL (www.thermoARL.com).]...

Figure 4.26 Micro infrared cell for liquid samples Reproduced from Haslam and co-workers, RSC [121]...

FIGURE 17>3 Expanded view of a demountable IR cell for liquid samples. Teflon spacers ranging from 0.015 to 1 mm thick are available. (Courtesy of Perkin-Elmer Corp.. Norwalk. CT.)... 

Figure 17-13b is an optical diagram of an adapter that fits into the cell area of most IR spectrometers and permits ATR measurements. Cells for liquid samples are also available. 

Cells for holding samples, or windows within the spectrometer must be made of infrared transmitting material. Table 2.1 lists approximate low wavenumber transmission limits for some optical materials used in infrared spectroscopy. All the materials listed transmit in the mid-IR above the transmission limit except for polyethylene, which is used below 600 cm" only, as it has absorption bands at higher frequencies. The transmission limits are not sharply defined and depend somewhat on the thickness of the material used. For example, a typical cell for liquid samples which is made of NaCl... 

Figure 7.42. Micro infrared cell for liquid samples.

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