Ab Initio Study of the Ionization of the DNA Bases:  Ionization Potentials and Excited States of the Cations

Cauët, Émilie; Dehareng, Dominique; Liévin, Jacques

doi:10.1021/jp0617625

Cited by 78 publications

(97 citation statements)

References 63 publications

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“…Table 3, ROMP2/6-311++G**). Similar trends were obtained by Cauët et al 39 We still keep the exception of o-tolualdehyde ranging outside the mentioned error regime, i.e., 0.35 eV error.…”

Section: Methods Comparison For the Calculation Of Adiabatic Ionizatiosupporting

confidence: 88%

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Photoionization of Atmospheric Aerosol Constituents and Precursors in the 7−15 eV Energy Region: Experimental and Theoretical Study

et al. 2008

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Photoionization mass spectrometry (PIMS) has been used to study the dissociative ionization of three anthropogenic atmospheric aerosol precursors (o-xylene, 2-methylstyrene, indene) and five of their main atmospheric degradation products (o-tolualdehyde, 2-methylphenol, o-toluic acid, phthalic acid, and phthaldialdehyde). Ionization and fragment appearance energies have been experimentally determined in the 7-15 eV photon energy regime. Moreover, intensive ab inito quantum chemical calculations have been performed to compute the first ionization energies and heats of formation of these compounds (including also phthalic anhydride). Several methods have been used, and the theoretical results are compared to the experimental values with the aim to find the best method to predict thermochemical data for similar molecules. The vacuum-UV fragmentation pathways following photoionization are discussed. The results of this work are important with respect to the analytical chemistry of these compounds since their basic gas phase ion energetics data are mostly unknown. They will help in interpreting real-time mass spectrometric measurements used for the study of organic aerosol formation in smog chambers and in the real atmosphere.

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“…Table 3, ROMP2/6-311++G**). Similar trends were obtained by Cauët et al 39 We still keep the exception of o-tolualdehyde ranging outside the mentioned error regime, i.e., 0.35 eV error.…”

Section: Methods Comparison For the Calculation Of Adiabatic Ionizatiosupporting

confidence: 88%

“…The separation of the geometry optimization and the energy calculation, treated each by two different methods, has been used with success in the past. [39][40][41][42] 3.2. Heats of Formation.…”

Section: Methodsmentioning

confidence: 99%

Photoionization of Atmospheric Aerosol Constituents and Precursors in the 7−15 eV Energy Region: Experimental and Theoretical Study

et al. 2008

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“…9,[15][16][17][18] Trofimov et al 9 measured a valence-shell PES of cytosine. By analyzing photoelectron energy and angular distributions, they concluded that only one tautomer, C2b (Fig.…”

Section: Introductionmentioning

confidence: 99%

“…Ab initio calculations of the IE's of the biologically relevant tautomer of cytosine have been reviewed by Roca-Sanjuan et al 16,17 and Cauet et al 17 Other tautomers were considered by Wolken et al who estimated the lowest IEs by DFT, MP2 and CCSD(T) calculations. 15 More reliable values of valence-shell VIEs of the five lowest-energy tautomers obtained using electron propagator methods were reported by Ortiz and coworkers.…”

Section: Introductionmentioning

confidence: 99%

Ionization of cytosine monomer and dimer studied by VUV photoionization and electronic structure calculations

Kostko

Bravaya

Krylov

et al. 2010

Phys. Chem. Chem. Phys.

124

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Photoionization of the cytosine dimer 2 SummaryWe report a combined theoretical and experimental study of ionization of cytosine monomers and dimers.Gas-phase molecules are generated by thermal vaporization of cytosine followed by expansion of the vapor in a continuous supersonic jet seeded in Ar. The resulting species are investigated by single photon ionization with tunable vacuum-ultraviolet (VUV) synchrotron radiation and mass analyzed using reflectron mass spectrometry. Energy onsets for the measured photoionization efficiency (PIE) spectra are 8.60±0.05 eV and 7.6±0.1 eV for the monomer and the dimer, respectively, and provide an estimate for the adiabatic ionization energies (AIE). The first AIE and the ten lowest vertical ionization energies (VIEs) for selected isomers of cytosine dimer computed using equation-of-motion coupled-cluster (EOM-IP-CCSD) method are reported. The comparison of the computed VIEs with the derivative of the PIE spectra, suggests that multiple isomers of the cytosine dimer are present in the molecular beam. The calculations reveal that the large red shift (0.7 eV) of the first IE of the lowest-energy cytosine dimer is due to strong inter-fragment electrostatic interactions, i.e., the hole localized on one of the fragments is stabilized by the dipole moment of the other. A sharp rise in the CH + signal at 9.20±0.05 eV is ascribed to the formation of protonated cytosine by dissociation of the ionized dimers. The dominant role of this channel is supported by the computed energy thresholds for the CH + appearance and the barrierless or nearly barrierless ionization-induced proton transfer observed for five isomers of the dimer.3

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“…13,14 However, previous single-photon ionization (SPI) studies of guanine have all been conducted utilizing the thermal vaporization method. Hush and Cheung, 15 using photoelectron spectroscopy (PES), reported a vertical ionization energy (VIE) of 8.24 eV.…”

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confidence: 99%

Experimental Observation of Guanine Tautomers with VUV Photoionization

et al. 2009

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Two methods of preparing guanine in the gas phase, thermal vaporization and laser desorption, have been investigated. The guanine generated by each method is entrained in a molecular beam, single-photon ionized with tunable VUV synchrotron radiation, and analyzed using reflectron mass spectrometry. The recorded photoionization efficiency (PIE) curves show a dramatic difference for experiments performed via thermal vaporization compared to that with laser desorption. The calculated vertical and adiabatic ionization energies for the eight lowest-lying tautomers of guanine suggest that the experimental observations arise from different tautomers being populated in the two different experimental methods.

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Ab Initio Study of the Ionization of the DNA Bases: Ionization Potentials and Excited States of the Cations

Cited by 78 publications

References 63 publications

Photoionization of Atmospheric Aerosol Constituents and Precursors in the 7−15 eV Energy Region: Experimental and Theoretical Study

Photoionization of Atmospheric Aerosol Constituents and Precursors in the 7−15 eV Energy Region: Experimental and Theoretical Study

Ionization of cytosine monomer and dimer studied by VUV photoionization and electronic structure calculations

Experimental Observation of Guanine Tautomers with VUV Photoionization

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