Collisions of 0–4 eV electrons with thin DNA films are shown to produce single strand breaks. The yield is sharply structured as a function of electron energy and indicates the involvement of ${\pi }^{*}$ shape resonances in the bond breaking process. The cross sections are comparable in magnitude to those observed in other compounds in the gas phase in which ${\pi }^{*}$ electrons are transferred through the molecule to break a remote bond. The results therefore support aspects of a theoretical study by Barrios et al. [J. Phys. B 106, 7991 (2002)] indicating that such a mechanism could produce strand breaks in DNA.

Thin films of the short single strand of DNA, GCAT, in which guanine (G) or adenine (A) have been removed, were bombarded under vacuum by 4 to 15 eV electrons. The fragments corresponding to base release and strand breaks (SB) were analyzed by high performance liquid chromatography and their yields compared with those obtained from unmodified GCAT. From such a comparison, it is shown that, using GCAT as a model system, (1) most SB result from electron capture by DNA bases followed by electron transfer to the phosphate group and (2) the initial capture probability depends on the coherence of the electron wave within the tetramer.

The complex physical and chemical reactions between the large number of low-energy (0–30 eV) electrons (LEEs) released by high energy radiation interacting with genetic material can lead to the formation of various DNA lesions such as crosslinks, single strand breaks, base modifications, and cleavage, as well as double strand breaks and other cluster damages. When crosslinks and cluster damages cannot be repaired by the cell, they can cause genetic loss of information, mutations, apoptosis, and promote genomic instability. Through the efforts of many research groups in the past two decades, the study of the interaction between LEEs and DNA under different experimental conditions has unveiled some of the main mechanisms responsible for these damages. In the present review, we focus on experimental investigations in the condensed phase that range from fundamental DNA constituents to oligonucleotides, synthetic duplex DNA, and bacterial (i.e., plasmid) DNA. These targets were irradiated either with LEEs from a monoenergetic-electron or photoelectron source, as sub-monolayer, monolayer, or multilayer films and within clusters or water solutions. Each type of experiment is briefly described, and the observed DNA damages are reported, along with the proposed mechanisms. Defining the role of LEEs within the sequence of events leading to radiobiological lesions contributes to our understanding of the action of radiation on living organisms, over a wide range of initial radiation energies. Applications of the interaction of LEEs with DNA to radiotherapy are briefly summarized.