Transmission sample conditions

Due to their sensitivity toward atmosphere, the sample conditioning had to preserve the sample from oxides or moisture interactions, and the surrounding from any linkages of vaporization of the sample, especially in actinides containing fluoride mixtures. A pellet was made of a mixture of boron nitride (BN) and sample powders, and pressed up to 61. This pellet was put between two plates in pyrolitic boron nitride, fixed hermetically with stainless steel screws. Thanks to their small size and simple geometry, inert toward molten fluorides and compatible with high temperature up to 1700 K and X-ray transmission, these cells fit easily in different furnaces [14]. 

Consistent sampling conditions are a necessity for careful quantitative work. In transmission spectrometry it is critical to fill the entire accessory aperture with the sample. If the actual sample area is smaller than the beam that passes through the aperture, stray light or excess radiation will reach the detector (Figure 9.2). The radiation that does not pass through the sample provides a spurious signal to the detector, and this excess radiation establishes a minimum transmittance. That is, no matter how strongly a sample absorbs, no band can have a transmittance below the minimum... 

One great advantage with digitized spectra is the capabihty to perform comparisons between the spectra of unknowns and reference spectra in a library. Infrared spectra are largely, but not completely, immune to collection conditions, that is, most spectral collection techniques (e.g., transmission, attenuated total reflection, diffuse reflection, photoacoustic spectrometry) will all produce approximately equivalent (but not identical) spectra if appropriate care is taken. Of course, some methods will be more successful than others for some samples or sample matrices, and those effects must be taken into account. Sample conditions are also important Spectra can change with temperature, solvent, or crystallinity, for example, and as the samples change their physical states, the infrared spectra will reflect those changes. 

The prediction of drop sizes in liquid-liquid systems is difficult. Most of the studies have used very pure fluids as two of the immiscible liquids, and in industrial practice there almost always are other chemicals that are surface-active to some degree and make the pre-dic tion of absolute drop sizes veiy difficult. In addition, techniques to measure drop sizes in experimental studies have all types of experimental and interpretation variations and difficulties so that many of the equations and correlations in the literature give contradictoiy results under similar conditions. Experimental difficulties include dispersion and coalescence effects, difficulty of measuring ac tual drop size, the effect of visual or photographic studies on where in the tank you can make these obseiwations, and the difficulty of using probes that measure bubble size or bubble area by hght or other sample transmission techniques which are veiy sensitive to the concentration of the dispersed phase and often are used in veiy dilute solutions. 

The importation of data from one electronic data system to another is improving. Some systems import weather data and sample chains of custody, such as shipping conditions, sample handling, etc., into the field raw data package. This allows for simplified reporting and tabulation. Data transmission over the Internet is improving and is already far superior to regular mail and even next-day delivery services. 

Let Ix, Iy and Iz be the intensity components of the fluorescence, respectively (Figure 6.3). If no polarizer is placed between the sample and the emission monochromator, the light intensity viewed by the monochromator is Iz + Iy, which is not proportional to the total fluorescence intensity (Ix + Iy + Iz). Moreover, the transmission efficiency of the monochromator depends on the polarization of the incident light and is thus not the same for Iz and Iy. To get a response proportional to the total fluorescence intensity, independently of the fluorescence polarization, polarizers must be used under magic angle conditions (see appendix, p. 196) a polarizer is introduced between the excitation monochromator and the sample and... 

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