Unoccupied electronic states in polythiophene as probed by XAS and RAS

Ikeura-Sekiguchi, Hiromi; Sekiguchi, Takuya

doi:10.1002/sia.2790

Cited by 15 publications

(24 citation statements)

References 17 publications

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“…Similar phenomena were observed in polythiophene and monomer units. [14] In contrast, almost the same features are observed in the unoccupied states of t 2 * . The equivalent spectral feature suggests that GMP and polyG form conduction band states through phosphate groups in analogy to DNA, [6] and phosphate ionic states are similar to each other because of different protonation states showing different spectral features.…”

Section: Introductionsupporting

confidence: 48%

Femto‐ and attosecond electron dynamics in 5′‐Guanosine monophosphate interface as probed by resonant Auger spectroscopy

Ikeura-Sekiguchi

Sekiguchi

2010

Surface & Interface Analysis

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To help in our understanding of the electron transport properties of deoxyribonucleic acid (DNA), it is useful to study the interfacial interaction between each nucleotide building block of DNA. Electron transfer properties between phosphate groups in microcrystalline 5 -Guanosin monophosphate (GMP) were probed using energy-dependent resonant Auger spectroscopy. Results show that the phosphate group of GMP forms an extended state along the phosphate directions similar to the case of DNA phosphate backbones. Electron delocalization time of the phosphate groups in GMP is faster than those of DNA, as estimated using the core-hole clock method. This suggests that interface between GMP phosphate groups would have the lowest tunneling barrier among DNA related systems. Although the π -π coupling of nucleobases is only recognized as charge-transfer pathway in DNA and related systems, another conduction pathway through phosphate groups would be possible. Copyright

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Section: Introductionsupporting

confidence: 48%

Femto‐ and attosecond electron dynamics in 5′‐Guanosine monophosphate interface as probed by resonant Auger spectroscopy

Ikeura-Sekiguchi

Sekiguchi

2010

Surface & Interface Analysis

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“… The calculated values are compared with experimental data of oligothiophenes (crystal powder) . Only the main transitions are shown.…”

Section: X‐ray Absorption Spectra Calculated With the Cvs‐adc(2)‐x Mementioning

confidence: 99%

“…For example, the peak structure of the core absorption spectra of the deoxyribonucleic acid (DNA) bases cytosine and uracil was analyzed to determine the population of specific tautomers . Furthermore, the band structure of polythiophenes as electrically conducting polymers has been probed to understand their conduction mechanisms . As the initially excited states are element specific and strongly localized, especially in K‐edge spectroscopy due to the contracted 1s orbital, they serve as chemical fingerprint and afford information about the chemical structure of a compound as well as the orientation between adsorbed molecules .…”

Section: Introductionmentioning

confidence: 99%

“…[4] Furthermore, the band structure of polythiophenes as electrically conducting polymers has been probed to understand their conduction mechanisms. [6] As the initially excited states are element specific and strongly localized, especially in K-edge spectroscopy due to the contracted 1s orbital, they serve as chemical fingerprint and afford information about the chemical structure of a compound as well as the orientation between adsorbed molecules. [7][8][9] Especially, NEXAFS techniques are used to probe excitations from the core region into unoccupied orbital levels of intramolecular bonds or extramolecular neighbors like surface atoms.…”

Section: Introductionmentioning

confidence: 99%

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Calculating core‐level excitations and x‐ray absorption spectra of medium‐sized closed‐shell molecules with the algebraic‐diagrammatic construction scheme for the polarization propagator

2014

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Core-level excitations are generated by absorption of high-energy radiation such as X-rays. To describe these energetically high-lying excited states theoretically, we have implemented a variant of the algebraic-diagrammatic construction scheme of second-order ADC(2) by applying the core-valence separation (CVS) approximation to the ADC(2) working equations. Besides excitation energies, the CVS-ADC(2) method also provides access to properties of core-excited states, thereby allowing for the calculation of X-ray absorption spectra. To demonstrate the potential of our implementation of CVS-ADC(2), we have chosen medium-sized molecules as examples that have either biological importance or find application in organic electronics. The calculated results of CVS-ADC(2) are compared with standard TD-DFT/B3LYP values and experimental data. In particular, the extended variant, CVS-ADC(2)-x, provides the most accurate results, and the agreement between the calculated values and experiment is remarkable.

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“…2, [5][6][7] For example, XAS provides information about the band structure of electrical conducting molecules or about the chemical structure of a compound as well as the orientation between adsorbed molecules. [8][9][10][11][12] Irradiation with X-rays near the K-shell absorption edge leads to spatially localized electronic excitations due to the strongly contracted 1s orbitals. Hence, Kedge spectra are in particular element specific and can serve as chemical fingerprints.…”

Section: Introductionmentioning

confidence: 99%

Analysis and comparison of CVS-ADC approaches up to third order for the calculation of core-excited states

Wenzel

Holzer

Wormit

et al. 2015

The Journal of Chemical Physics

126

196

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The extended second order algebraic-diagrammatic construction (ADC(2)-x) scheme for the polarization operator in combination with core-valence separation (CVS) approximation is well known to be a powerful quantum chemical method for the calculation of core-excited states and the description of X-ray absorption spectra. For the first time, the implementation and results of the third order approach CVS-ADC(3) are reported. Therefore, the CVS approximation has been applied to the ADC(3) working equations and the resulting terms have been implemented efficiently in the adcman program. By treating the α and β spins separately from each other, the unrestricted variant CVS-UADC(3) for the treatment of open-shell systems has been implemented as well. The performance and accuracy of the CVS-ADC(3) method are demonstrated with respect to a set of small and middle-sized organic molecules. Therefore, the results obtained at the CVS-ADC(3) level are compared with CVS-ADC(2)-x values as well as experimental data by calculating complete basis set limits. The influence of basis sets is further investigated by employing a large set of different basis sets. Besides the accuracy of core-excitation energies and oscillator strengths, the importance of cartesian basis functions and the treatment of orbital relaxation effects are analyzed in this work as well as computational timings. It turns out that at the CVS-ADC(3) level, the results are not further improved compared to CVS-ADC(2)-x and experimental data, because the fortuitous error compensation inherent in the CVS-ADC(2)-x approach is broken. While CVS-ADC(3) overestimates the core excitation energies on average by 0.61% ± 0.31%, CVS-ADC(2)-x provides an averaged underestimation of -0.22% ± 0.12%. Eventually, the best agreement with experiments can be achieved using the CVS-ADC(2)-x method in combination with a diffuse cartesian basis set at least at the triple-ζ level.

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Unoccupied electronic states in polythiophene as probed by XAS and RAS

Cited by 15 publications

References 17 publications

Femto‐ and attosecond electron dynamics in 5′‐Guanosine monophosphate interface as probed by resonant Auger spectroscopy

Femto‐ and attosecond electron dynamics in 5′‐Guanosine monophosphate interface as probed by resonant Auger spectroscopy

Calculating core‐level excitations and x‐ray absorption spectra of medium‐sized closed‐shell molecules with the algebraic‐diagrammatic construction scheme for the polarization propagator

Analysis and comparison of CVS-ADC approaches up to third order for the calculation of core-excited states

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