Tiago Cunha, Mr.

RABBIT PhD student (SFRH/BD/52538/2014)

“Negative Ion Formation in Potassium-Purine Molecule Collisions" (2014-2018);

The effects of ionising radiation on biological material have been studied on the tissue scale for many years. However, research to understand the processes at a molecular level has begun only recently. Relatively few experiments have been carried out on the effects of ionising radiation and secondary electrons on key biological molecules such as DNA and its constituent bases. Cross-sectional results for these interactions are highly relevant to the use of radiation in medicine. Today, it is possible to isolate biomolecules including uracil, thymine, and adenine (bases of RNA and DNA) in the gas phase. The current research crossed molecular beam apparatus will be used to study electron transfer on DNA bases (nucleotides) by atom (potassium) – molecule (DNA bases) collisions. The experiment thus represents a novel perspective spanning two traditionally independent research areas: electron attachment and electron harpooning studies of gas phase molecules. Total partial cross sections will be obtained in an energy range from about a few eV up to several hundreds of eV. These experiments will allow us to probe whether such electron transfer process is a correct model for electron transport in DNA or whether electron harpooning by bound electrons supplied in K - molecule scattering is a more appropriate model for electron transport under physiological conditions.