Knowledge Bank

Absorption spectra for light polarized along the a, b and c crystallographic directions of adenine-HCl single crystals have been obtained by a Kramers-Kronig transformation of reflection spectra ($6500\backslash AA-1850\backslash AA$). The transition moment directions and oscillator strengths of the four observed bands are obtained. Crystal perturbations leading to intensity borrowing among bands and internal field effects are considered. The derived single molecule properties are used to calculate the optical properties of polyadenylic acid double helix.