The project was devoted to the investigation of two processes – electron-transfer mediated decay (ETMD) and interatomic Coulombic electron capture (ICEC). The major goals of the project were 1) to develop the theory and computational methods for studying ETMD and ICEC, and 2) to uncover the potential inherent to ETMD and ICEC and exploit it. These objectives were fully accomplished and the investigation of ICEC, and especially of ETMD, is now a rapidly growing field of research. Stimulated by our results, a number of experimental groups from all over the world have performed experiments and are now actively working on studying and exploiting the different aspects of these processes.
During the project, our team developed a palette of theoretical and computational methods and techniques allowing high-quality calculations for obtaining static and dynamic properties of the ETMD and ICEC processes in different systems ranging from small van-der-Waals clusters to doped helium droplets and microsolvated atoms and molecules. Using these tools, we were able to elucidate various aspects of the studied processes and predict new mechanisms from the non-local decay family. Our collaborations with several experimental groups were strongly intensified, giving rise to a series of spectacular experiments on the subject, confirming the important role the ETMD mechanism plays in distributing energy and charges to the environment after a local deposition of ionizing radiation. Inspired by these results, other experimental groups entered the field and performed and/or are currently preparing new experiments on the subject.
We found that ETMD is an important pathway for the neutralization of multiply charged ions produced in an Auger decay in condensed media and demonstrated for the first time the existence of de-excitation cascades that consist of several non-local decay processes, including different variants of ETMD, which distribute the initially deposited energy to the environment, creating secondary electrons and radical cations. These relaxation pathways are expected to be ubiquitous in biomatter and important for understanding the radiation damage. We also developed an ab initio approach allowing to compute ICEC cross sections in experimentally interesting systems and showed that the process can be highly efficient in mirosolvated atoms and molecules, additionally enhanced by the electronic resonances of the solvent. In addition, we formulated and investigated theoretically a new vibrational energy transfer process, which accelerates the rate of vibrational relaxation in molecules in the presence of atomic or molecular anions by several orders of magnitude.
