Abstract
The bacteriocidal effect of 248 nm line of KrF excimer laser is compared with that of 253.7 nm line of conventional mercury lamp. In considering the slight difference of absorption coefficient of DNA in bacteria at these lines, sterilizing effect of both UV lights is almost same at the laser intensity below 5×188 W/m2. In the laser intensity exceeds 5×188 W/m2, survival ratio is increased. Saturation of the light absorption to the bacteria at such high intensity is considered to occure and the saturation intensity is reduced to be 3.3×109W/m2. However this saturation effect cannot be explained from the already known rate constants of the UV excitation processes of nucleic acid to damage DNA in bacteria. To use the KrF excimer laser for high sterilization, it is suitable to increase the repetition rate by keeping the irradiation intensity below the saturation intensity.
