Electronic states of some simple ethers studied by vacuum ultraviolet absorption and near-threshold electron energy-loss spectroscopy

Bremner, L. J.; Curtis, Martin G.; Walker, Isobel C.

doi:10.1039/ft9918701049

Cited by 51 publications

(64 citation statements)

References 23 publications

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“…Although measured at lower resolution, the EELS spectra agree well with the photoabsorption data for the band position. Our data also appears to be in very good agreement with the literature data of Davidson et al [28] and Bremner et al [32] in both energy position and absolute cross section, although our resolution is better than that of Bremner et al [32]. The photoabsorption spectrum is composed of a low energy band peaking at 6.6 eV, on which very sharp features are superimposed.…”

Section: Neutral Ground Statesupporting

confidence: 81%

“…Hence, based on our theoretical results, we assign the first absorption band to the lowest energy transitions for the C 2 and C s conformers, see Fig. 3 with the previous work of Bremner et al [32]. Again, the agreement between theory and experiment is excellent and allows a straightforward interpretation of this spectral region.…”

Section: Neutral Excited Statesmentioning

confidence: 87%

“…Tam member was in agreement with the previous work, but interestingly, their vibrational analysis of the first spectral band did not involve a second electronic origin. Bremner et al [32] reexamined the VUV photoabsorption spectrum of THF extending the excitation energy range up to the LiF cut off at 11.8 eV allowing further Rydberg series to be analysed.…”

Section: Introductionmentioning

confidence: 99%

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Electronic states of neutral and ionized tetrahydrofuran studied by VUV spectroscopy and ab initio calculations

et al. 2008

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The electronic spectroscopy of isolated tetrahydrofuran (THF) in the gas phase has been investigated using high-resolution photoabsorption spectroscopy in the 5.8-10.6 eV with absolute cross section measurements derived. In addition, an electron energy loss spectrum was recorded at 100 eV and 10° over the 5-11.4 eV range. The He(I) photoelectron spectrum was also collected to quantify ionisation energies in the 9-16.1 eV spectral region. These experiments are supported by the first high-level ab initio calculations performed on the excited states of the neutral molecule and on the ground state of the positive ion. The excellent agreement between the theoretical results and the measurements allows us to solve several discrepancies concerning the electronic state spectroscopy of THF. The present work reconsiders the question of the lowest energy conformers of the molecule and its population distribution at room temperature.

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Section: Neutral Ground Statesupporting

confidence: 81%

Section: Neutral Excited Statesmentioning

confidence: 87%

Section: Introductionmentioning

confidence: 99%

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Electronic states of neutral and ionized tetrahydrofuran studied by VUV spectroscopy and ab initio calculations

et al. 2008

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“…Both shape (one particle) resonances and core-excited (one hole, two particles) Feshbach resonances are expected in this energy range, but the bands in figure 7 can be assigned to shape resonances because Feshbach resonances generally affect vibrational excitation only very weakly. An additional indicator for an assignment to shape resonances rather than Feshbach resonances is the fact that both bands are substantially broader (∼3 eV) than the Rydberg bands (∼0.4 eV) [34], which would be the parent states of the Feshbach resonances. The shapes of the curves in figure 7 resemble the shapes of the vibrational excitation functions reported by Lepage et al [4] for the condensed THF-both exhibit two very broad bands-although the bands of the condensed THF are at lower energies by about 2 eV.…”

Section: Vibrational Excitation Cross Sectionsmentioning

confidence: 99%

Absolute angle-differential elastic and vibrational excitation cross sections for electron collisions with tetrahydrofuran

Allan

2007

J. Phys. B: At. Mol. Opt. Phys.

110

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Absolute angle-differential elastic and vibrational excitation cross sections for electron collisions with tetrahydrofuran were measured in the energy range 0.1-20 eV, extending existing measurements to lower energies. The elastic cross sections were measured as a function of scattering angle from 10• to 180• at energies of 2 eV, 6 eV, 10 eV and 20 eV, and as a function of electron energy at 45• , 90• , 135• and 180• . The agreement with previous measurements and with the published theoretical work was generally satisfactory. The RamsauerTownsend minimum was observed at low energies, down to 0.24 eV at 180• . Three additional minima were observed at 1.13, 4.74 and 15.3 eV in the 180• elastic cross section. Vibrational excitation cross sections are reported as a function of electron energy from the threshold to 16 eV. They reveal threshold peaks and broad bands at 6.2 and 10.8 eV, attributed to shape resonances, in agreement with theoretical predictions, although the calculated energies are generally somewhat higher. A broad enhancement of the CH 2 scissoring vibration is observed around 2.6 eV, implying a low-lying (shape) resonance similar to that observed earlier in cyclopropane.

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“…With an identical probability for the distribution of bases in the DNA, n s for each base is 2.34 × 10 13 cm −2 , while its value for the sugar and phosphate groups is 9.36 × 10 13 cm −2 , ε i and σ i are mainly obtained from available EEL spectra; these have been measured by HREELS for the DNA bases, and tetrahydrofuran (THF) and phosphoric acid, as analogues of the sugar and phosphate groups in the DNA backbone, respectively. 21,36,37 For electron energies where such experimental data were not available, [38][39][40][41][42] The ε i and σ i were extracted from theoretical data. EEL spectra have been obtained from a single electron collision regime.…”

Section: A Nanodosimetric Modelmentioning

confidence: 99%

Correlation between energy deposition and molecular damage from Auger electrons: A case study of ultra-low energy (5-18 eV) electron interactions with DNA

2014

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Purpose-The present study introduces a new method to establish a direct correlation between biologically related physical parameters (i.e., stopping and damaging cross sections, respectively) for an Auger-electron emitting radionuclide decaying within a target molecule (e.g., DNA), so as to evaluate the efficacy of the radionuclide at the molecular level. These parameters can be applied to the dosimetry of Auger electrons and the quantification of their biological effects, which are the main criteria to assess the therapeutic efficacy of Auger-electron emitting radionuclides.Methods-Absorbed dose and stopping cross section for the Auger electrons of 5-18 eV emitted by 125 I within DNA were determined by developing a nanodosimetric model. The molecular damages induced by these Auger electrons were investigated by measuring damaging cross section, including that for the formation of DNA single-and double-strand breaks. Nanoscale films of pure plasmid DNA were prepared via the freeze-drying technique and subsequently irradiated with low-energy electrons at various fluences. The damaging cross sections were determined by employing a molecular survival model to the measured exposure-response curves for induction of DNA strand breaks.Results-For a single decay of 125 I within DNA, the Auger electrons of 5-18 eV deposit the energies of 12.1 and 9.1 eV within a 4.2-nm 3 volume of a hydrated or dry DNA, which results in the absorbed doses of 270 and 210 kGy, respectively. DNA bases have a major contribution to the deposited energies. Ten-electronvolt and high linear energy transfer 100-eV electrons have a similar cross section for the formation of DNA double-strand break, while 100-eV electrons are twice as efficient as 10 eV in the induction of single-strand break.Conclusions-Ultra-low-energy electrons (<18 eV) substantially contribute to the absorbed dose and to the molecular damage from Auger-electron emitting radionuclides; hence, they should be considered in the dosimetry calculation of such radionuclides. Moreover, absorbed dose is not an appropriate physical parameter for nanodosimetry. Instead, stopping cross section, which describes the probability of energy deposition in a target molecule can be an appropriate nanodosimetric parameter. The stopping cross section is correlated with a damaging cross section a)Author to whom correspondence should be addressed. CIHR Author ManuscriptCIHR Author Manuscript CIHR Author Manuscript (e.g., cross section for the double-strand break formation) to quantify the number of each specific lesion in a target molecule for each nuclear decay of a single Auger-electron emitting radionuclide.

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Electronic states of some simple ethers studied by vacuum ultraviolet absorption and near-threshold electron energy-loss spectroscopy

Cited by 51 publications

References 23 publications

Electronic states of neutral and ionized tetrahydrofuran studied by VUV spectroscopy and ab initio calculations

Electronic states of neutral and ionized tetrahydrofuran studied by VUV spectroscopy and ab initio calculations

Absolute angle-differential elastic and vibrational excitation cross sections for electron collisions with tetrahydrofuran

Correlation between energy deposition and molecular damage from Auger electrons: A case study of ultra-low energy (5-18 eV) electron interactions with DNA

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