“…One of the motivations behind these photoionization studies is to gain a better understanding of the direct effects of high-energy radiation on DNA which leads to strand breaks (SchulteFrohlinde, 1986a(SchulteFrohlinde, , 1986b(SchulteFrohlinde, , 1989. The radiationinduced double-strand breaks are the most serious damage to DNA in cells which, if unrepaired, lead to cell transformation, mutation and cell death (Ward, 1975(Ward, , 1990Schulte-Frohlinde, 1987a, 1987b.…”