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Direct Damage of Deoxyadenosine Monophosphate by Low-Energy Electrons Probed by X‑ray Photoelectron Spectroscopy
journal contribution
posted on 2020-02-25, 18:34 authored by Sramana Kundu, Micah J. Schaible, Aaron D. McKee, Thomas M. OrlandoLow-energy (3–25
eV) electron interactions with multilayers
of 2′-deoxyadenosine 5′-monophosphate (dAMP) were probed
using X-ray photoelectron spectroscopy (XPS). Understanding how electrons
damage the nucleotide dAMP, which is a building block of DNA, can
give insight into how the DNA undergoes radiation damage. Chemical
modifications to the constituent units of the nucleotide were revealed
in situ through monitoring of the O 1s, C 1s, and N 1s elemental transitions.
It is shown that direct electron irradiation causes decomposition
of both the base and sugar subunits, as well as cleavage of glycosidic
and phosphoester bonds. Incident electrons undergo inelastic energy
losses, including creation of core-excited resonances above 3–4
eV. In the condensed phase, these resonances decay via autoionization,
producing electronically excited targets and <3 eV electrons. The
excited states dissociate and the slow (<3 eV) electrons are captured
by neighboring molecules, forming molecular shape resonances that
can lead to bond rupture. Since the observed chemical changes were
similar at all incident electron energies studied, they can be primarily
attributed to formation and decay of transient negative ions. Damage
enhancements in the energy ranges typical of all scattering resonances
are expected, with the damage probability dominated by the low-energy
shape resonances.
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Deoxyadenosine Monophosphatephosphoester bondsinelastic energy losseselectron interactionsXPSconstituent unitsN 1shape resonancesDamage enhancementslow-energy shape resonancesresonances decaycore-excited resonancesincident electron energiesradiation damageLow-Energy Electrons ProbedeVsugar subunitsenergy rangesIncident electronschemical changesDNAO 1electrons damagechemical modificationselectron irradiation causes decompositionC 1Direct Damagebuilding blockdamage probabilityX-ray photoelectron spectroscopynucleotide dAMPbond rupture
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