Electron stimulated desorption of H− from thin films of thymine and uracil

Abstract

Articles you may be interested inElectron stimulated desorption of anions from native and brominated single stranded oligonucleotide trimers J. Chem. Phys. 136, 075101 (2012); 10.1063/1.3685587 Comparative study of electron stimulated positive-ion desorption from LiCl and 1-ethyl-3-methylimidazolium bis[trifluoromethylsulfonyl]imide Electron stimulated desorption of anionic fragments from films of pure and electron-irradiated thiophene Intrinsic and extrinsic factors in anion electron-stimulated desorption: D − from deuterated hydrocarbons condensed on Kr and water ice filmsWe present measurements of low energy ͑0-38 eV͒ electron stimulated desorption of H Ϫ from room temperature thin films of pure thymine ͑T͒ and uracil ͑U͒, condensed on polycrystalline Pt, and describe in detail the experimental methods required for such studies. The nominal film thicknesses are estimated to range from 0.08 to 2.7 monolayers; sublimation of the films at 69°C ͑T͒ and 82°C ͑U͒ onto the room temperature Pt substrate leads to nonuniform film growth, i.e., volumetric clustering, particularly in the submonolayer regime. H Ϫ formation by electron impact occurs via dissociative electron attachment ͑DEA͒ to the molecules, and results in strong desorption peaks near 8.6 eV for either molecule, whereas above 12-13 eV nonresonant dipolar dissociation dominates the desorption yields. Comparison of the present condensed phase results with gas phase measurements suggests that the desorbing H Ϫ produced at the DEA peak are mainly the result of CH bond cleavage, while near the desorption threshold of about 5 eV NH bond cleavage via DEA may also contribute to the H Ϫ signal. The present measurements suggest that localized resonances involving DNA bases, leading to the formation of anions and their associated neutral radical moieties, contribute to the resonant signature observed recently in the strand break yields of double stranded DNA irradiated with 3-20 eV electrons.

Electron stimulated desorption of anions containing Oxygen and Nitrogen from self-assembled monolayers of DNA

“…For all of the DNA components [6][7][8][9][10][11][12][13], the formation of resonances (i.e., TNI) that dissociate into a stable anionic and radical fragments was observed. One of the remaining challenges is to identify, in a long DNA chain, which TNI state of the different basic constituents ( the bases, sugar and phosphate…”

“…To better understand the mechanisms underlying DNA damage through electron attachment, studies have examined interactions of LEE with various components of DNA such as the bases [6][7][8][9][10], deoxyribose analogues [ 11,12], and the phosphate group [13] of the backbone in gas and solid phases. For all of the DNA components [6][7][8][9][10][11][12][13] [14] investigated the electron stimulated desorption (ESD) of anions induced by 3-20 eV electron impact on lyophilized thin films of linear and supercoiled DNA.…”

“…For all of the DNA components [6][7][8][9][10][11][12][13] [14] investigated the electron stimulated desorption (ESD) of anions induced by 3-20 eV electron impact on lyophilized thin films of linear and supercoiled DNA. Their results suggested that dissociative electron attachment (DEA) is the process that leads to the formation of the observed desorbed anions (H¯, O¯, and OH¯).…”

Absolute cross sections for electronic excitations of cytosine by low energy electron impact

“…Most of them concern the formation of various anion fragments produced by dissociative electron attachment (DEA) to these molecules in gas phase 8 -19 and sublimated as thin films. 20,21 Few studies have examined their electronic and vibrational excitations by electron energy loss (EEL) spectroscopy in the gas phase. 22 -24 So far, not much attention have been devoted on the determination of the absolute CS values for these different collision processes.…”

Density functional theory for the photoionization dynamics of uracil

“…Thus, the suggestion that metastable electron capture of the large amount of non-thermal secondary electrons produced upon the interaction of ionizing radiation with the cell environment [5] by the various DNA components could initiate the formation of SSBs and DSBs, stimulated a wealth of experimental work on electron collisions with gaseous [6][7][8][9] and thin films DNA and RNA bases [10]. Recently theoretical studies have also given a better understanding of these insights [11,12].…”