Also, P varies in a sinusoidal manner between these two extremes (P = ± 0.38) for the fibers oriented with an intermediate angle  (Figures and, blue lines). The strongly polarized blue emission (em < 500 nm) from the nanofibers varies strongly with the angle of fiber orientation (), indicating a high degree of intermolecular ordering and a preferential average orientation of the (R)-1NDI molecular units along the nanofiber. In addition, a negative polarization for horizontally (north/south) oriented fibers and, conversely, a positive polarization for vertically (east/west) oriented fibers indicates that the (R)-1NDI units emit strong blue polarized light perpendicular to the long axis of the fibers when excited with linear polarization. Therefore, (R)-1NDI molecular units are self-assembled in a perpendicular manner to the long axis of the fiber, with some degree of angle variations as highlighted by the maximum polarization amplitude (± 0.