Trigonal groups

T0815 Trigon Group, L.L.C., ARCHON In Situ Mixer... 

According to the developer, the Trigon Group, L.L.C., system is more effective when a solution of nonionic, biodegradable detergent is used. 

Table 62 Character table of some trigonal groups and their double groups...

These diffraction groups have the same reflection conditions as the following trigonal groups P—, P3 --, P--c, and P-c-. Therefore, they are indistinguishable from systematic absences using powder data. ly I = 3n If, I = 6 . 

In Table 12.7 we see that r4 for the group 4/m differs by one term from r4 for the group 4lmmm. The extra-term in 4/m splits those reflections that are nonequivalent but coincident in the absence of the macrostress. The same is valid for the trigonal group 3. The anisotropic peak broadenings caused by microstress are also different for coincident but non-equivalent peaks." ... 

A structural study of potassium and rubidium amidoberyllates, prepared in a reaction between a solution of potassium or rubidium in liquid ammonia with metallic beryllium, reveals that the compounds belong to the space group Pbca, with a = 12.88, 6 = 11.21, c = 13.19 A for KBe(NH2) and a = 12.96, 6 = 11.55, and c = 13.48 A for RbBe(NH2)3. The structures are composed of trigonal groups of [Be(NH2)3] and M " ions. I.r. and Raman spectral data arc also available. ... 

The R lattice is only compatible with the trigonal groups. 

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