Abstract
Very broad σ∗ resonances, which are responsible for threshold structures and dissociative attachment in electron collisions with hydrogen halides, are also important in electron-impact bond-breaking in nucleobases and amino acids. We investigate this mechanism in more detail by carrying out model calculations of the N-H bond breaking in the uracil molecule. Although the σ∗ resonance is extremely broad at the equilibrium nuclear geometry, it is stabilized fast when the N-H bond is stretched, and this produces a substantial dissociative attachment cross section. In addition, very pronounced vibrational Feshbach resonances are seen below vibrational excitation thresholds. To incorporate the effect of a cluster environment in the dissociative electron attachment process, we develop further the multiple scattering theory for this process and calculate the dissociative attachment cross section for the CF3Cl molecule embedded in the (H2O)6 cluster.
Highlights
Interaction of low-energy electrons with DNA nucleobases, organic acids, and amino acids is of great significance for the description of the molecular mechanisms in radiation damage [1,2,3,4,5,6,7,8]
We investigate this mechanism in more detail by carrying out model calculations of the N-H bond breaking in the uracil molecule
To incorporate the effect of a cluster environment in the dissociative electron attachment process, we develop further the multiple scattering theory for this process and calculate the dissociative attachment cross section for the CF3Cl molecule embedded in the (H2O)6 cluster
Summary
Interaction of low-energy electrons with DNA nucleobases (thymine, adenine, cytosine, and guanine), organic acids, and amino acids is of great significance for the description of the molecular mechanisms in radiation damage [1,2,3,4,5,6,7,8]. When high-energy radiation interacts with a biological medium, it produces free radicals and low-energy electrons. This is a important process in aqueous solutions as the biological damage induced by free radicals from the radiolysis of water far exceeds that by direct energy deposition to DNA [9]. With regard to DEA in electron collisions with biological molecules, we will be interested in the process of hydrogen loss, i.e. the reaction e + M → (M − H)− + H where (M−H)− denotes the closed shell anion formed by the ejection of a neutral hydrogen radical from the temporary negative ion. To study the effects of a water environment, we place the attaching molecule in a water cluster and use the multiple-scattering theory [14, 15] to investigate how the water molecules affect the attachment amplitude and the DEA cross sections
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