centrosymmetric การใช้

• A polar axis can occur only in non-centrosymmetric structures.
• centrosymmetric environment are electric-dipole forbidden by the Laporte rule.
• Isomeric with violanthrone is isoviolanthrone, which has a centrosymmetric structure.
• This is the case of non-centrosymmetric achiral structure.
• The term polar is often used for those point groups which are neither centrosymmetric nor chiral.
• It has a centrosymmetric angular structure.
• Third, a perfect single crystal with a non-centrosymmetric structure can develop a giant photovoltage.
• The wurtzite structure is non-centrosymmetric ( i . e ., lacks inversion symmetry ).
• If the original structure and inverted structure are identical, then the structure is " centrosymmetric ".
• They were able to employ the Sayre equation in centrosymmetric structure, developing the so-called direct methods.
• An important point about ferroelectrics is that they cannot exist in a "'centrosymmetric "'crystal.
• The same rule also applies to " f-f " transitions in centrosymmetric complexes of lanthanides and actinides.
• As the crystal is cooled below the Curie temperature, it shifts gradually into a more and more non-centrosymmetric configuration.
• Still, even for non-centrosymmetric case, inverted structure in some cases can be rotated to align with the original structure.
• Due to this, wurtzite crystals can ( and generally do ) have properties such as piezoelectricity and pyroelectricity, which centrosymmetric crystals lack.
• For example, in a perfectly centrosymmetric crystal, "'P "'is usually defined by convention to be exactly zero.
• This method has been used to derive wetting properties of polymer melts on polymer brushes of the same species that may yield very unusual non-centrosymmetric lamellar structures.
• The two techniques are complementary and comparison between the two can provide useful structural information such as in the case of the rule of mutual exclusion for centrosymmetric molecules.
• In particular, for three such related beams in a centrosymmetric structure, the phases can only be 0 or \ pi and the Sayre equation reduces to the triplet relationship:
• Additionally intermolecular N " H?" ?" ?" O hydrogen bonds are also present combining two molecules into a centrosymmetric dimer ( 8-membered ring is formed ).