ქიმიის ტერმინთა განმარტებითი ლექსიკონი

Mesophase formed by a non-chiral compound or by the racemate of a chiral compound in which the spatial distribution of the molecular centers of mass is devoid of long-range positional order and the molecules are, on average, orientationally ordered about a common axis defined as the director and represented by the unit vector n.

Note 1: See Fig. for an illustration of the molecular organization in a uniaxial nematic mesophase.

Note 2: The unit vector, n(See Fig..)

Note 3: The direction of n is usually arbitrary in space.

Note 4: The extent of the positional correlations for the molecules in a nematic phase is comparable to that of an isotropic phase although the distribution function is necessarily anisotropic.

Note 5: From a crystallographic point of view, the uniaxial nematic structure is characterised by the symbol D_¥h in the Schoenflies notation (¥/mm in the International System).

Note 6: Since the majority of nematic phases are uniaxial, if no indication is given, a nematic phase is assumed to be uniaxial but, when there is the possibility of a biaxial as well a uniaxial nematic, a uniaxial phase should be denoted as N_u.

Fig. A representation of the molecular organization in a uniaxial nematic mesophase.