Infrared crystallinity index

Keywords infrared spectroscopy, transmitted light petrography, illite crystallinity index, 4-acid digestion ICP-MS, orogenic gold... 

Infrared Crystallinity Index. A measure of the relative degree of crystallinity was determined from the infrared spectra obtained in the preceding section by reporting the ratio of the optical density of the band at 1372"1 (7.29/mi) to that at 2900 cm 1 (3.45/xm). According to Nelson and O Connor (15), the crystallinity index measured in this way compares well with data from x-ray diffraction, density measurements, and accessibility measured by moisture sorption. 

DP Turnbull s Blue Test (Arb. Units) Infrared, (A OD) Infrared Crystallinity Index... 

DP Infrared COOH Content Injrared Crystallinity Index... 

FIGURE 5.21 Infrared (IR) crystallinity index (Cl) 1429 versus accessibility by the Br2 method for different cellulose fiber. 

The fabrics were characterized by measuring their tensile and tear strengths, extent of oxidation via Turnbull s blue test and infrared ctroscopy, infrared crystallinity index and molecular weight. 

Microscopy (qv) plays a key role in examining trace evidence owing to the small size of the evidence and a desire to use nondestmctive testing (qv) techniques whenever possible. Polarizing light microscopy (43,44) is a method of choice for crystalline materials. Microscopy and microchemical analysis techniques (45,46) work well on small samples, are relatively nondestmctive, and are fast. Evidence such as sod, minerals, synthetic fibers, explosive debris, foodstuff, cosmetics (qv), and the like, lend themselves to this technique as do comparison microscopy, refractive index, and density comparisons with known specimens. Other microscopic procedures involving infrared, visible, and ultraviolet spectroscopy (qv) also are used to examine many types of trace evidence. 

The films were deposited onto NaCl or KBr discs to facilitate examination by infrared transmission. Substrates of platinum, aluminum, ALOn, and fused SiO approximately one cm. in diameter were prepared for the rate studies. The index of refraction and isotropic character of film specimens obtained from the substrates and/or gas inlet tube were determined with a petrographic microscope. Debye-Scherrer x-ray diffraction powder patterns were made to establish whether the films were amorphous or crystalline. 

Optically transparent crystalline and glassy oxide films have been obtained from some metal alkyls and alkoxides in a microwave discharge plasma at a substrate temperature of 200°C [210]. Chemical compositions were controlled by infrared absorption and refractive index measurements and the data obtained were compared with the stoichiometric compounds. The optical data of such plasma-deposited oxides are listed in Table 7a [210]. 

A special sampling technique often applied for infrared studies of biological systems is attenuated total reflection spectroscopy or ATR spectroscopy. With this technique, the infrared beam is guided through a transparent medium of high refractive index (plate, often crystalline material) in such a way that several total reflections take place at the surfaces. Ideally, if the surfaces are clean, the infrared beam is not attenuated. However, if an infrared absorber is deposited onto the surface, the infrared... 

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