| 1. |
- Wassdahl, N., et al.
(författare)
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Soft x-ray emission studies of adsorbates
- 1992
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Ingår i: Physical Review Letters. - 0031-9007. ; 69:5, s. 812-815
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Tidskriftsartikel (refereegranskat)abstract
- Soft x-ray emission spectroscopy is for the first time applied to surfaces and adsorbates. Surface sensitivity is achieved by employing synchrotron radiation in grazing incidence for the excitation. We present O K emission from adsorbed atomic oxygen on Ni(100) and Cu(100) and molecular CO on Ni(100). The observed spectral features correspond to the occupied 2p partial density of states of the adsorbates.
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| 2. |
- Antonsson, H, et al.
(författare)
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VIBRATIONAL MOTION AND GEOMETRICAL STRUCTURE IN ADSORBED CO STUDIED BY CORE LEVEL PHOTOELECTRON-SPECTROSCOPY
- 1990
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Ingår i: Journal of Electron Spectroscopy and Related Phenomena. - 0368-2048. ; 54, s. 601-613
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Tidskriftsartikel (refereegranskat)abstract
- High resolution core level spectra from CO adsorbed on clean and hydrogen precovered Ni(100) and CO adsorbed on Cu(100) are presented. The core level binding energy is shown to be sensitive to the adsorption site. Cluster calculations reproduce the general trend of the binding energy shifts between the on top and hollow sites of CO/Ni(100). In the coadsorption system CO/H/Ni(100) three different adsorption sites have been observed with a maximum binding energy shift of 2.6 eV for the Ols level. The temperature dependence of the Cls and Ols line profiles in CO/Ni(100) has been carefully investigated. The temperature dependent broadening is due to thermal excitations of frustrated translations parallel to the surface. The spectra from CO on Cu(100) show no temperature dependence below 200K.
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| 3. |
- Grama, D, et al.
(författare)
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Pancreatic tumors in multiple endocrine neoplasia type 1 : clinical presentation and surgical treatment
- 1992
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Ingår i: World Journal of Surgery. - 0364-2313 .- 1432-2323. ; 16:4, s. 611-618
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Tidskriftsartikel (refereegranskat)abstract
- Among 33 patients with endocrine pancreatic tumors due to multiple endocrine neoplasia type 1 (MEN-1), 19 (58%) patients had hypergastrinemia, 7 (21%) patients had hyperinsulinism, and 7 (21%) patients had clinically non-functioning lesions. At least one gross tumor was found in all patients undergoing pancreatic surgery, including those with negative localization studies prior to operation. The patients also had additional macroscopic tumors as well as numerous microadenomas, and the lesions frequently were positive for immunostaining with multiple hormones, mainly pancreatic polypeptide, insulin, glucagon, and somatostatin. Duodenal endocrine lesions were found in 4 of 5 investigated patients and stained with gastrin and somatostatin antibodies. Distal, mainly subtotal pancreatic resection, was performed in 18 patients, eventually combined with caput tumor enucleation or duodenotomy, while a few patients underwent only tumor enucleation or a Whipple procedure. The long-term outcome of operation was most favorable in patients with hyperinsulinism; only 1 patient had clinical recurrence. Patients with hypergastrinemia experienced only transitory lowering of serum gastrin values after pancreatic surgery and 47% of them had or developed metastases. Such tumor spread was seen in 57% of the patients with non-functioning lesions. Nine patients died from progressive tumor disease during follow-up. Consistent with previous studies, we found that surgery is indicated in MEN-1 patients with hyperinsulinism even if a lesion is not visualized by radiology. In addition, these indications should be extended to also include patients with only biochemical markers of disease, including elevations of gastrin, as these indicate the presence of gross tumors.
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| 4. |
- Nilsson, A., et al.
(författare)
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Photoabsorption and the unoccupied partial density of states of chemisorbed molecules
- 1992
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Ingår i: Chemical Physics Letters. - : Elsevier BV. - 0009-2614. ; 197:1-2, s. 12-16
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Tidskriftsartikel (refereegranskat)abstract
- The 1s to 2π* resonances have been studied for CO strongly chemisorbed on Ni(100) and weakly chemisorbed on Cu(100) using high resolution X-ray absorption spectroscopy. We show that the spectra can be consistently described in terms of the local density of unoccupied 2π* electron states with the Fermi level obtained from corresponding X-ray photoelectron spectra. The core hole is demonstrated to induce large shifts in the unoccupied 2π* density of states.
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| 5. |
- Zdansky, E. O F, et al.
(författare)
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Electronic structure of atomic adsorbates from x-ray-absorption spectroscopy : Threshold effects and higher excited states
- 1993
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Ingår i: Physical Review B (Condensed Matter). - 0163-1829. ; 48:4, s. 2632-2641
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Tidskriftsartikel (refereegranskat)abstract
- Atomic C, N, and O chemisorbed on Ni(100) have been studied by x-ray-absorption spectroscopy. The atomic 2p orbitals are shown to form hybrid orbitals with the Ni 3d and 4sp bands. The spectral contributions from these hybrids are identified at the absorption threshold and in a region 6-12 eV above this. Between those regions, states derived from atomic 3p and higher np orbitals are observed. The threshold region shows vibrational and dynamical effects, which are discussed in connection with the corresponding photoemission spectra. The substrate Ni 2p3/2 x-ray-absorption spectrum is also presented. Its large similarity to the Ni 2p3/2 x-ray photoemission spectrum is discussed.
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