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- Li, Z. S, et al.
(författare)
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Radiative properties of neutral germanium obtained from excited-state lifetime and branching-ratio measurements and comparison with theoretical calculations
- 1999
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Ingår i: Physical Review A (Atomic, Molecular and Optical Physics). - 1050-2947. ; 60:1, s. 198-208
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Tidskriftsartikel (refereegranskat)abstract
- Using time-resolved UV laser-induced fluorescence from a laser-produced plasma, natural radiative lifetimes have been measured for 21 levels of Ge I belonging to the odd-parity 4p4d, 4p5d, and 4p6s configurations. Stimulated Brillouin scattering in water has allowed us to compress Nd:YAG laser pulses pumping a dye laser (where YAG denotes yttrium aluminum garnet), thus yielding 1-ns tunable laser pulses to enable accurate measurements of short lifetimes. Branching ratios of Ge I have been measured by inductively coupled plasma emission spectrometry, the intensity calibration being performed by means of Ar lines emitted by a hollow-cathode lamp. The experimental lifetimes and branching ratios have been combined in order to provide a set of accurate transition probabilities for the 4p-5s and 4p-4d transitions. A relativistic Hartree-Fock; calculation, taking configuration-interaction and polarization effects into account, has been combined with a least-squares optimization procedure of the Slater and spin-orbit integrals in order to test the ability of this approach to correctly predict radiative properties of the group-IV elements. Good agreement between experimental and theoretical transition probability values has been achieved for most of the transitions considered.
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| 6. |
- McGinnis, S, et al.
(författare)
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Use of oxygen-stabilized C-60 films for selective chemical vapor deposition
- 1997
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Ingår i: APPLIED PHYSICS LETTERS. - : AMER INST PHYSICS. ; 70:5
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Thin C-60 films exposed to ultraviolet/visible light in the presence of oxygen were used as a selective mask for tungsten chemical vapor deposition on silicon substrates. An uptake of oxygen in the fullerene films as well as a significant increase in the
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| 8. |
- Norin, L, et al.
(författare)
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On the Existence of Transition-Metal Fullerides: Deposition and Characterization of TixC60
- 1998
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Ingår i: Chemistry of Materials. - : American Chemical Society (ACS). - 0897-4756 .- 1520-5002. ; 10:4, s. 1184-1190
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Tidskriftsartikel (refereegranskat)abstract
- Titanium fulleride films (TixC60) were prepared by coevaporating Ti and C60 onto moderately heated substrates (~100 C) in an ultrahigh vacuum system. The TixC60 films were all amorphous according to X-ray diffraction and exhibited a gray, metallic luster different from the brown color of pristine C60. The compound also appeared to be metallic or semiconducting as no charging was observed in X-ray photoelectron spectroscopy (XPS) in contrast to analyses of pure C60. XPS of the films showed a maximum titanium content of about 5.3-5.5 at. % (Ti~3.5C60). For higher titanium contents, carbide formation was observed. The XPS analyses also showed binding energy shifts and line broadening effects consistent with the formation of chemical bonds between Ti and C60. Raman spectroscopy showed a softening of the Ag(2) mode upon Ti incorporation (-4 cm-1/Ti atom) which is consistent with a partial charge transfer from Ti to C60. The TixC60 films oxidized immediately upon air exposure. However, XPS and Raman spectroscopy show persistent differences from pristine C60 which might indicate that another phase, TixOyC60, is formed upon oxidation.
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