The radicals induced by nitrogen ion beam irradiating UNA and its bases have been studied with ESR method. The experimental results show that the induced radicals at room temperature are ionic. Concentrations of the radicals for different samples increase with increasing ion dose. Various samples have been tested with ESR method during the stored time of more than one month under the dry conditions at room temperature （10-20℃）

no big change was observed for the radicals

showing a quite long life.