Damaging Intermolecular Energy and Proton Transfer Processes in Alpha‐Particle‐Irradiated Hydrogen‐Bonded Systems

Abstract

Although the biological hazard of alpha-particle radiation is well-recognized, the molecular mechanisms of biodamage are still far from being understood. Irreparable lesions in biomolecules may not only have mechanical origin but also appear due to various electronic and nuclear relaxation processes of ionizeds tates produced by an alphaparticle impact. Tw os uch processes were identified in the present study by considering an acetylene dimer,abiologically relevant system possessing an intermolecular hydrogen bond. The first process is the already well-established intermolecular Coulombic decayo fi nner-valence-ionized states.T he other is an ovel relaxation mechanism of dicationic states involving intermolecular proton transfer.B oth processes are very fast and trigger Coulomb explosion of the dimer due to creation of charge-separated states.T hese processes are general and predicted to occur also in alpha-particle-irradiated nucleobase pairs in DNAmolecules.

Quantum size effect affecting environment assisted electron capture in quantum confinements

“…[36][37][38] In the sense of a Feshbach resonance, an electron in the single-electron-excited state of one partner A − * relaxes to a lower-energy state while its excess energy becomes available for ionization of the other partner B − . Compared to the young prediction of ICEC, however, inter-Coulombic decay is already well established in various fields, among them helium droplets, 39 hollow atoms, 40 as well as biological systems, 41,42 and nanostructures as fullerenes 43 or quantum films. 44,45 Different ways to achieve ICD resonance have been studied: namely radiation, 46 , α-particle, 42 and ultimately electron impact, [27][28][29]47 the pathway we are discussing hereafter.…”

Computing the Ultrafast and Radiationless Electronic Excited State Decay of Cytosine and 5‐methyl‐cytosine Cations: Uncovering the Role of Dynamic Electron Correlation

“…The effects of high‐energy radiation on DNA are and have been of interest to the scientific community as they are considered to be responsible for well‐known damaging instances such as DNA cross links, base releases and single/double strand breaks occurring under ionising or Alpha‐particle irradiation . Moreover, the emergence of spectroscopic methods in the vacuum and extreme UV (VUV/EUV) and the soft and hard X‐ray regimes further motivates their study, as these high‐energy spectroscopic techniques allow observing photo‐excitation and photoionisation processes with unprecedented accuracy and enable monitoring the electronic and nuclear dynamics separately for the first time …”

A Missing Puzzle in Dissociative Electron Attachment to Biomolecules: The Detection of Radicals

“…Moreover, because of the Coulomb explosion of two cationic radicals that are formed during this process, the system decomposes. Therefore, ICD has been proposed to be another important factor in base-pair fragmentation [18] and DNA-strand breaks [19,20]. For example, it has been estimated that the ICD that produces radicals and LEEs may contribute up to 50% of the SSBs at the DNA-water interface during low-energy ionization events.…”