Widths and fluorescence yields of atomic<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>L</mml:mi></mml:math>-shell vacancy states

Chen, Mau Hsiung; Crasemann, Bernd; Mark, Hans

doi:10.1103/physreva.24.177

Cited by 386 publications

(151 citation statements)

References 19 publications

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“…Then, the contributions from all cationic fragments were summed up and normalized to the photoabsorption cross-sections measured by Ishii & Hitchcock (1987). Assuming a negligible fluorescence yield due to the low carbon atomic number (Chen et al 1981) and an ionic fragment production in the present photon energy range, it is possible to consider that all absorbed photons lead to cation formation. Inner shell photoabsorption and the subsequent photoionization process may produce instabilities in the molecular structure (nuclear rearrangements), producing a transient molecule that breaks down following different dissociation pathways.…”

Section: Methodsmentioning

confidence: 99%

Single and Double Photoionization and Photodissociation of Toluene by Soft X-Rays in a Circumstellar Environment

Monfredini¹,

Fantuzzi²,

Nascimento³

et al. 2016

ApJ

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The formation of polycyclic aromatic hydrocarbons (PAHs) and their methyl derivatives mainly occurs in the dust shells of asymptotic giant branch (AGB) stars. The bands at 3.3 and 3.4 μm, observed in infrared emission spectra of several objects, are attributed C-H vibrational modes in aromatic and aliphatic structures, respectively. In general, the feature at 3.3 μm is more intense than that at 3.4 μm. Photoionization and photodissociation processes of toluene, the precursor of methylated PAHs, were studied using synchrotron radiation at soft X-ray energies around the carbon K edge using time-of-flight mass spectrometry. Partial ion yields of a large number of ionic fragments were extracted from single and 2D-spectra, where electron-ion coincidences have revealed the doubly charged parent molecule and several doubly charged fragments containing seven carbon atoms with considerable abundance. Ab initio calculations based on density functional theory were performed in order to elucidate the chemical structure of these stable dicationic species. The survival of the dications subjected to hard inner shell ionization suggests that they could be observed in the interstellar medium, especially in regions where PAHs are detected. The ionization and destruction of toluene induced by X-rays were examined in the T Dra conditions, a carbon-rich AGB star. In this context, a minimum photodissociation radius and the half-life of toluene subjected to the incidence of the soft X-ray flux emitted from a companion white dwarf star were determined.

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Section: Methodsmentioning

confidence: 99%

Single and Double Photoionization and Photodissociation of Toluene by Soft X-Rays in a Circumstellar Environment

Monfredini¹,

Fantuzzi²,

Nascimento³

et al. 2016

ApJ

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“…It may be noted that inclusion of many body effects is expected to decrease the photoionization cross sections [28,29] and CK transition probabilities [30] thereby resulting in lower values of the theoretical XRP cross sections. Further, the observed significant differences between the present measured σ Lγ2 , 3 (exp) XRP cross sections and different sets of calculated values cannot be explained in terms of anisotropic emission of these X-rays.…”

Section: Discussionmentioning

confidence: 99%

“…Further, the IPA models are inadequate in handling, particularly, the CK transitions and were found to overestimate (~10%) the L 1 subshell CK transition rates for heavy elements. [30] Therefore, more refined theoretical predictions of the photoionization cross sections, fluorescence, and CK yields at energies in vicinity of the absorption edges of different elements incorporating the many-body effects in the existing models along with better understanding of solid-state effects are highly desirable to apprehend the observed differences between measured and theoretical values.…”

Section: Discussionmentioning

confidence: 99%

Synchrotron radiation induced X‐ray production cross sections of ₆₆Dy at energies across its L_i (i = 1–3) subshell absorption edges

et al. 2017

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) emission lines have been measured by tuning the incident synchrotron radiation at energies over the range 7.8-9.2 keV and 10-370 eV above the respective L i (i = 1-3) absorption edges. These measurements aim to check the reliability of the independent particle approximation models used to generate the theoretical data sets of different physical parameters required to calculate the XRP cross sections and also investigate the influence of many body effects on the photoionization process. The present measured Lγ 2,3 (originating from decay of the L 1 subshell vacancies) XRP cross sections are found to be significantly higher than different sets of theoretical values, whereas a good agreement is generally observed for the various other XRP cross sections and relative intensities.

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“…To eliminate the PCI shift on the kinetic energies we simulated the line shapes using the formula given by Armen et al [34]. Moreover, for this purpose we used the lifetime broadenings of 2.82, 3.04, and 3.35 eV for the thresholds L 3 ,L 2 , and L 1 , respectively [29]. We want to point out that the PCI shift cannot be neglected even several hundred eV above the respective ionization threshold.…”

Section: Fig 7 Comparison Of the Experimental (Data Points) And Thementioning

confidence: 99%

Detailed assignment of normal and resonant Auger spectra of Xe near the L edges

et al. 2017

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We present a comprehensive experimental and theoretical investigation on the LMM, LMN, and LNN normal Auger spectra of xenon, which reveal excellent agreement with theory when core-hole lifetimes of the two-hole final states are taken into account. Generally, the spectra turned out to be highly complex due to a strong overlap of the Auger transitions subsequent to 2s1/2 , and 2p3/2 ionization. This overlap is due to the splitting of the three initial L core holes and the different final M and N core holes being on the same order of magnitude of several hundred eV. The Auger transitions are assigned in detail based on the theoretical results. Most of the MM, MN, and NN final states are described well based on jj coupling. In addition, we present a detailed assignment of the resonant LM 45 M 45 Auger transition subsequent to the 2s → 6p, 7p and 2p → 5d, 6d excitations.

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Widths and fluorescence yields of atomicL-shell vacancy states

Cited by 386 publications

References 19 publications

Single and Double Photoionization and Photodissociation of Toluene by Soft X-Rays in a Circumstellar Environment

Single and Double Photoionization and Photodissociation of Toluene by Soft X-Rays in a Circumstellar Environment

Synchrotron radiation induced X‐ray production cross sections of ₆₆Dy at energies across its L_i (i = 1–3) subshell absorption edges

Detailed assignment of normal and resonant Auger spectra of Xe near the L edges

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Widths and fluorescence yields of atomicL-shell vacancy states

Cited by 386 publications

References 19 publications

Single and Double Photoionization and Photodissociation of Toluene by Soft X-Rays in a Circumstellar Environment

Single and Double Photoionization and Photodissociation of Toluene by Soft X-Rays in a Circumstellar Environment

Synchrotron radiation induced X‐ray production cross sections of 66Dy at energies across its Li (i = 1–3) subshell absorption edges

Detailed assignment of normal and resonant Auger spectra of Xe near the L edges

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Synchrotron radiation induced X‐ray production cross sections of ₆₆Dy at energies across its L_i (i = 1–3) subshell absorption edges