The crystal structure of auramine perchlorate: correlation of the results with specular reflection spectroscopy.
The x-ray analysis of auramine perchlorate has been performed in order to establish the orientation of the cationic chromophoric group in the crystal for comparison with the orientation that was proposed on the basis of specular reflection studies. The compound crystallizes with two molecules per unit cell in space group P1 and cell parameters a = 8.86 A, b = 9.69 A, c = 11.27 A, alpha = 97 degrees 40', beta = 99 degrees 34', and gamma = 106 degrees 16'. The orientation of the chromophore is in good agreement with the crystal model. Other features of the structure are the hydrogen bonding scheme of the perchlorate ion, the highly distorted chromophoric group, and the planar dimethylamine substituents.
Structural Features from Reflection Spectra: Orientation of 1, 3,-bis-(Dimethylamino) trimethinium Perchlorate Molecules in the Crystal
Abstract If the orientation of a molecular electronic transition moment with respect to the molecular framework is known, reflection spectra of crystalline samples on various faces may be used to locate the molecules in question. This can be done through projection of the transition moment on the faces, or through use of the optical indicatrix. The two methods are briefly compared, and the preferred indicatrix method is applied to crystals of the dye 1,3-bis-(dim-ethylamino)trimethinium perchlorate. Along each principal axis of the indicatrix, best fit values for reasonant frequency, plasma frequency, and damping constant are obtained in the frequency range of the first singlet. Parameters of the crystal structure having to do with the orientation of the dye molecules are then deduced from this information.
Normed units in abelian group rings
We compute explicitly the isomorphic structure of the normalized unit group of an abelian group ring under some minimal natural restrictions on the group basis and the coefficient ring. This enlarges affirmations due to Chatzidakis-Pappas (J. London Math. Soc., 1991) and Mollov (Publ. Math. Debrecen, 1971).