Slow-crystallized sample spectra

Additional information is available by subtracting spectra taken at different temperatures for the same sample. Since the position of the film was not altered as the temperatures varied, a 1 1 subtraction is a systematic method to illustrate the thermal eflFects. The spectra at the two temperature extremes for a slow-crystallized sample are subtracted in Figure 20. The 909 and 990 cm vinyl bands narrow in width, increase in intensity, and shift to slightly higher frequency as the temperature is decreased. The crystalline absorptions at 1050 and 1176 cm shift to lower frequency and sharpen considerably. The 1303 cm amorphous absorption shifts its maximum to 1300 cm and possibly increases in intensity. The 1353 cm" band remains fixed in position. The most intense amorphous band, 1369 cmmoves to 1371 cm at 78 K and has an intensity increase. These results are shown clearly in the difference spectrum. Similar results are obtained for the isopentane-quenched sample before and after annealing. 

The method of digitally subtracting spectra is illustrated in Figure 10. This subtraction shows that the isopentane-quenched sample has twice as much amorphous material as the one which was slow-crystallized. The expansion factor for plotting of the difiFerence spectrum rela-... 

Some Properties of Xe(OSOtF)2.— Die Raman spectrum is compared with those of FXeOSOtF and StOoFt in Table III. Single crystals of Xe(OS02F)t were obtained by slow evaporation of a HF solution and fragmentary precession photograph data, from such a crystal, provided for the indexing of the X-ray powder data given in Table IV. The unit cell is monoclinic with a = 7.94, b = 13.7, c = 6.84 A, 0 = 96 . A small sample of Xe(OSOtF)2 under a dynamic vacuum at 20 slowly decomposed but none of the compound collected in the limbs of a U tube, cooled at —75°, provided to trap it. 

As in Fig. 1, when classifying NMR into pulsed NMR, solution NMR and solid-state NMR, it is convenient to know which NMR technique should be used for a liquid, solution, solid, liquid crystal or gel sample. For example, using the solution NMR spectrum of a polymer gel, that is, a high-resolution solution NMR spectrum, there is a combination of rapid movement and slow moving parts that prevents signal yield. Therefore, to obtain complete information on the polymer gel, various NMR techniques need to be combined. In this section, examples in which NMR is used for studies on microscopic and macroscopic structures and dynamics will be introduced. 

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