Résumé
The first hyperpolarizability of the DNA bases Thymine and Cytosine were determined by Hyper Rayleigh Scattering in neat water despite their low solubility. Due to the low intensity levels collected, count statistics was performed instead of the standard dilution procedure. The first hyperpolarizability were found to be 2.99+/-0.44x10^-30 esu for Thymine and 3.35+/-0.21x10^-30esu for Cytosine. Due to its weak solubility, only an upper limit of 1.82+/-0.10x10^-30 esu could be set for Adenine. The first hyperpolarizability of Guanine could not be measured because of its too weak solubility. Theoretical static and 800 nm dynamic first hyperpolarizability tensor elements were also computed with Gaussian 09 for comparison.