N in-plane

The intensity changes of the N-H and C=0 bands are mostly responsible for the intermolecular forces between the polymer chains. Let us now determine how the polymer backbone is affected by the external stretching forces. In order to do so, tj e band due to the C-C aromatic stretchir g at 1408 cm" and the C-N in-plane bending at 1261 cm modes will be examined. Figure 4, traces A through F, depicts the rheo-photoacoustic spectra in the 1450-1200 cm" region. 

The same method of approach may be adopted in dealing with the body-centred cubic lattices I lie unit of which is shown in Fig. 1H. All of the atoms in this lattice lie in the (t 10) and (200) sets of planes, which incluele respectively the planes AEFB and HJKL. In order to include the body-centred atom N in planes of the type (111) the set must be written (222). The simplest index planes for a body-centred cubic lattice are thus those with the indices (110), (200) and (222). 

The detection and the assignment of out-of-plane polarized transitions is hence very direct and easy in disc-like-molecules like pyrimidine, pyrazine and pyridazine, where, as expected, the well isolated n ->tt out-of-plane and the 7T-> n in-plane transitions show negative and positive L.D. respectively (Figure 2). The dichroic ratio AOD/OD of an out-of-plane transition, besides being opposite signed is also twice as intense as the dichroic ratio of an in-plane... 

Primary aliphatic nitriles 580-555 17.24-18.02 m-s m C-C=N in-plane def vib, C=N tram to carbon atom... 

Aromatic nitriles 580-540 17.24-18.52 s m combination of C=N in-plane bending vib and out-of-plane bending vib of aromatic ring... 

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