Optical Nonlinearity in DNA (Deoxyribonucleic acids) Films

摘要

We have used Raman and Brillouin scattering to study the role of water, ions base sequence, and crystal morphology on the structure and dynamics of DNA. We find that the interactions between DNA double helices (as measured by the frequency of Raman bands in the solid state), elastic properties, internal geometry (conformation) and optical properties are all dominated by the specific counter ion, changing in a systematic manner with counter ion hydrated radius. The primary hydration shell relaxes at about 2.5 GHz and consists of about one monolayer of water molecules attached to the DNA by one hydrogen bond, on average. The hyperpolarizibility of DNA films is about 1% of that of quartz. (aw)