Azimuthal layer line

The dimensions of the xylan unit cell are slightly different a = b = 1.340 nm, (fibre axis) = 0.598 nm.) Atkins and Parker T6) were able to interpret such a diffraction pattern in terms of a triple-stranded structure. Three chains, of the same polarity, intertwine about a common axis to form a triple-strand molecular rope. The individual polysaccharide chains trace out a helix with six saccharide units per turn and are related to their neighbours by azimuthal rotations of 2ir/3 and 4ir/3 respectively, with zero relative translation. A similar model for curdlan is illustrated in Figure 6. Examinations of this model shows that each chain repeats at a distance 3 x 0.582 = 1.746 nm. Thus if for any reason the precise symmetrical arrangement between chains (or with their associated water of crystallization) is disrupted, we would expect reflections to occur on layer lines which are orders of 1.746 nm. Indeed such additional reflections have been observed via patterns obtained from specimens at different relative humidity (4) offering confirmation for the triple-stranded model. 

Figure 7 Incident electron energy dependence of the X v = 0, 1, 2, 3 vibrational and the a Ag (v = 0) electronic loss scattered intensities from a 10-layer film of O2 condensed on Pt(lll). was set at 10° with 6 at 45° and the azimuth at 10°. Also shown is the energy dependence of the inelastic background intensity located just before the v = 1 loss peak onset at Aif = 0.16 eV along with that contributing to each energy-loss profile (dashed lines). (From Ref. 118.)...

Fig. 9. Best fit two-layer model for ULM. Left shows the fast shear-wave polarization, < ), as a function of the back-azimuth (Baz) to individual events. Right shows the delay time, 5/, between the fast and slow shear waves as a function of back-azimuth. The continuous line shows the predicted variation for a two-layer model where ( ) = 85.0° and fit = 0.4 s in the upper layer and < ) = 50.0° and 5t= 1.3 sin the lower layer and for a frequency...

Fig. 2.4 Azimuthal orientational distribution functions of an 8CB monolayer on a rubbed polyimide-coated substrate (solid line), and an 8CB interfacial layer between a rubbed polyimide-coated surface and bulk 8CB (dashed line). Reproduction by permission from [6],...

---