LAUSR

The optical absorption, fluorescence, phosphorescence in UV and visible spectral range, and effect of light irradiation on spectral properties of DNA with the presence of nickel ions are studied. The quantity of nickel ions varies from 1 ion per 500 base pairs of DNA to 2 ions per base pair. Three important features fixed: the shape of fluorescence and phosphorescence spectra of the DNA do not change in presence of Ni, but their intensity depends on the number of nickel ions in solution; phosphorescence intensity decreases more rapidly than fluorescence; the small decrease of DNA photodegradation rate in presence of Ni is observed. The average of triplet exciton path length evaluated from the dependence of phosphorescence/fluorescence intensity ratio on the relative concentration of nickel ions is 30–20 DNA pair sequence length. It was proposed that nickel ions interact in the outer side of DNA with the phosphate groups and do not penetrate intra macromolecular space.