FILM DICHROISM .2. LINEARLY-POLARIZED ABSORPTION-SPECTRA OF ACRIDINE-DYES IN THE STRETCHED POLYVINYL-ALCOHOL) FILMS

The linear dichroic absorption spectra of the protonated and quaternized acridine dyes were measured in the UV and visible regions by the stretched film technique. The dyes examined were acridine, 10-methylacridine, Proflavine, Trypaflavine, Acridine Yellow, 10-Methylacridine Yellow, Acridine Orange, and 10-Methylacridine Orange, all of which belong to the C//2//v point symmetry group. Poly(vinyl alcohol) was used as a film matrix. The absorption spectrum of each dye was resolved into the long-axis and short-axis polarized components. Two orthogonally-polarized electronic transitions (the **1L//a and **1L//b bands) of 3,6-disubstituted acridine dyes were reduced to overlap in the visible region of the spectra. The orientation factors K//y and K//z of each dye were evaluated at a constant degree of stretching and were related to the geometry of the dye molecule.