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  • 1
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The photoionization from outer- and inner-valence shells of SnCl2 vapor, induced by means of molecular effusive beam technique and dispersed synchrotron radiation as an ionizing source, reveals new spectroscopic and dynamical aspects in this molecule. Spectral features related to states with main Cl 3s contribution are observed for the first time in a molecule with Cl-metal bonds. The corresponding ionization energy (IE) is 22.61 eV. A breakdown of the one-particle model is exhibited in the inner-valence spectral region. These experimental findings are compared with the theoretical predictions obtained by performing configuration interaction (C.I.) calculations for the molecular ionic states. A strongly resonant behavior in the cross section of some main lines and satellites is experimentally pointed out by tuning the excitation photon energy through resonances localized at 25.03 and 26.11 eV. CI calculations for the transition energies relative to 4d excitations have been carried out and explain the aforementioned phenomena in terms of autoionizing 4d→LUMO lowest unoccupied molecular orbital 8b1 excitations. Finally, Auger processes following the relaxation of Sn 4d hole in the free molecule SnCl2 are observed.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 102 (1995), S. 3555-3565 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The full-valence photoelectron (PE) spectrum of SnCl4 excited by synchrotron radiation in the ultraviolet (UV) region is reported here for the first time, and compared with the analogous spectrum of SnCl2 previously published. Electron correlation effects in the different valence spectral regions are experimentally and theoretically analyzed for both tin chlorides. The theoretical results are obtained at ab initio 2h-1p CI level. Total-ion-yield (TIY) spectra excited by synchrotron radiation are obtained for both molecules in the Sn 4d−1 thresholds region for the first time. Sn 4d excited states in the two chlorides are hence identified through the resonant features displayed by the TIY spectra. The assignment is in good qualitative agreement with the excitation energies and oscillator strengths calculated at ab initio CI level. Clear differences exhibited by both PE and TIY spectra reported in this work originate from the different metal oxidation state in the two apparently similar chlorides, or equivalently, from the different involvement of the valence atomic orbitals of tin to form the chemical bonds of the molecule. Inner-valence ionizations in the investigated molecules are shown to be a sensitive probe of the halogen chemical environment, being related to the Sn–Cl bond polarization.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0301-0104
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Journal of Electron Spectroscopy and Related Phenomena 57 (1991), S. R1-R6 
    ISSN: 0368-2048
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Chester : International Union of Crystallography (IUCr)
    Journal of synchrotron radiation 5 (1998), S. 565-568 
    ISSN: 1600-5775
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: This paper reports the present stage of commissioning of the gas-phase photoemission beamline at Elettra, Trieste. The beamline is designed for atomic and molecular science experiments with high-resolution and high-flux synchrotron radiation. It consists of an undulator source, variable-angle spherical-grating monochromator and two experimental stations. The design value of the energy range is 20 to 800 eV with a specified resolving power of over 10000. The procedure adopted for calibration of this type of monochromator is discussed. At present a resolving power up to 20000 and a range up to 900 eV have been measured. Absorption spectra taken at the argon LII,III-edge and at the nitrogen, oxygen and neon K-edges are as sharp as, or sharper than, any reported in the literature. The instrumental broadening is well below the natural line-width making it difficult to quantify the resolution; this problem is discussed.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1432-0509
    Keywords: Key words: Ultrasound—Esophageal cancer—Cervical lymph node metastasis.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. Background: The detection of cervical lymph node metastases plays an important role in staging of patients affected by esophageal cancer to perform the best therapeutic approach. Methods: We report our experience concerning the ultrasound evaluation of the cervical area in 174 patients with esophageal cancer. Ultrasonographic evaluation of the neck can be done with a 7.5- or 10 MHz transducer in all cases, with selective scanning of the lymph node chains of the internal jugular veins and supraclavicular regions. The short-to-long axis ratio (S/L) was a useful way to detect lymph node metastasis. Histopathologic diagnoses were obtained by sonographically guided fine-needle aspiration biopsy. Results: At ultrasound examination, we found 18 (10.3%) patients with metastatic cervical nodes. Of these, 17 (94.4%) had metastatic cervical lymph nodes confirmed by cytology from fine-needle biopsy. Lymph node exceeding 5 mm in long axis and with an S/L over 0.5 showed a higher incidence of metastasis than those with an S/L under 0.5. Our experience shows a high incidence of lymph node metastases in patients with esophageal cancer localized to the thoracic supracarinal tract and in patients with cervical and lower esophageal cancer. Conclusion: In the ultrasound evaluation of nodes, the most useful parameters are size of nodes, heterogeneity of internal echoes, morphology of the margins, and the deformation caused by compressive instrumental manipulation. These criteria, indicated by the Japanese Society for Esophageal Diseases, yield a high sensitivity and diagnostic specificity when the ultrasonographic studies are performed.
    Type of Medium: Electronic Resource
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