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.
The electronic spectra of diphenylmethane dyes
Abstract The absorption and emission spectra, along with their relative polarizations have been obtained for several diphenylmethane dyes. When the transitions are correlated with those of the triphenylmethane dyes, such as Crystal Violet, it is found that the number of observed transitions decreases, as do the number of low-energy resonance structure. The absorption intensities are calculated for the low-energy transitions, and good agreement is found with those observed.
Low Resolution Electronic Spectrum of Crystalline para‐Dimethoxybenzene with Application to Benzene
The spectrum of a thin (0.37μ) crystal of para‐dimethoxybenzene for light incident on the 001 plane and polarized along the a and b crystallographic axes is given. From this, approximate spectra are determined for the two in‐plane directions of the molecule. Absorption at 2900 A is polarized predominately in a direction perpendicular to the line joining the substituents while absorption at 2350 A is parallel to this line. The 2600 and 2000 A absorptions in benzene are related respectively to the 2900 and 2350 A bands in dimethoxybenzene and consequently the benzene bands are found to arise from transition to upper states of species B 2u and B 1u respectively. The relation to conventional orbital theory is briefly discussed.