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21.
Steven C. Moss John F. Knudsen Robert C. Bowman Jr. Paul M. Adams Duane D. Smith 《Applied Surface Science》1991,50(1-4):337-340
We have used picosecond transient reflectance techniques to measure the near-surface characteristics of ion-implanted GaAs. These non-destructive laser-based diagnostic techniques allow measurement of the modification of near-surface properties at relatively low implant fluences. Photothermal phenomena dominate these results and yield important information concerning the extent of implant-induced materials modification. 相似文献
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G.P. Knudsen 《Solid State Communications》1984,49(11):1045-1047
Inelastic neutron scattering measurements have been performed on the elpasolite Cs2NaNdCl6 in the cubic phase. It is found that the cubic-to-tetragonal phase transition at 137 K is driven by a zone-center soft phonon mode. The mode is of symmetry Λ′15 and corresponds to a rotation of the Cl6 octahedra. The characteristics of the phase transition are similar to those observed in some compounds of the perovskite and antifluorite structures. 相似文献
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The composition of iron(III) precipitates prepared by different methods was investigated by Mossbauer and infrared spectrometry. The principal constituents were identified as α-FeOOH, β-FeOOH, α-Fe2O3, and the van der Giessen precipitate, α-Fe2O3· nH2O. Effects of chloride ion and formic acid on the products of precipitation were studied. 相似文献
26.
G. Løvhøiden J.R. Lien S. El-Kazzaz J. Rekstad C. Ellegaard J.H. Bjerregaard P. Knudsen P. Kleinheinz 《Nuclear Physics A》1980,339(3):477-502
The level structures of the 145, 147, 149Nd nuclei up to about 5 MeV excitation energy have been investigated with the (3He, α) reaction at 24 MeV. Additional 17 MeV (d, t) data have been obtained for 147, 149Nd. The angular distributions have been analyzed with standard DWBA calculations, and spectroscopic factors have been deduced. Two groups of states carrying h single-particle strength may be associated with the ? [514] and ? [505] Nilsson orbitals. A considerable amount of high-l single-particle strength may be found in the continuum observed in the (3He, α) spectra above 3 MeV in all the nuclei. 相似文献
27.
Beheshti N Bu H Zhu K Kjøniksen AL Knudsen KD Pamies R Hernandez Cifre JG García de la Torre J Nyström B 《The journal of physical chemistry. B》2006,110(13):6601-6608
The formation of associative networks in semidilute aqueous solutions of hydrophobically modified hydroxyethylcellulose (HM-HEC) is dependent on intermolecular hydrophobic interactions. Addition of hydroxypropyl-beta-cyclodextrin (HP-beta-CD) monomers to the system provides decoupling of these associations via inclusion complex formation with the polymer hydrophobic tails. Results from viscosity, polymer NMR self-diffusion, and dynamic light scattering (DLS) measurements show that the hydrophobic interactions in HM-HEC solutions are effectively suppressed when the level of HP-beta-CD addition increases. Small-angle neutron scattering (SANS) results reveal that the large-scale association complexes in HM-HEC solutions are strongly diminished when the concentration of HP-beta-CD rises. The time correlation data obtained from the DLS experiments unveiled the existence of two relaxation modes: one single exponential at short times followed by a stretched exponential at longer times. The fast mode is always diffusive, whereas the slow mode exhibits progressively stronger wavevector dependence as the intensity of the hydrophobic interactions increases. This feature, as well as the accompanying drop of the stretched exponential beta as the HP-beta-CD concentration decreases, is attributed to enhanced hydrophobic interactions and can be well rationalized in the framework of the coupling model of Ngai. 相似文献
28.
Bjørn Tore Knudsen 《Czechoslovak Journal of Physics》1997,47(9):925-929
The WA97 experiment is a part of the CERN heavy-ion program. The experiment aims to measure enhanced strangeness production as a signal of the phase transition from a Quark-Gluon Plasma. The first run for the experiment was in the autumn 1994, when CERN accelerated lead-ions in the SPS ring for the first time. The WA97 experiment have used silicon microstrip and pixel detectors with technology which have never been used before. It is shown that even the triply strange can be reliably measured in the experiment. 相似文献
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Walderhaug H Knudsen KD 《Langmuir : the ACS journal of surfaces and colloids》2008,24(19):10637-10645
Microemulsion samples of a polyoxyethylene trisiloxane surfactant, water, and 1-decanol are investigated using pulsed field gradient NMR and small-angle neutron scattering (SANS) to determine the solution structure. The surfactant/decanol weight ratio has been kept constant at values of 10:1, 8:1, and 6:1 under variation of water content. The temperature was 32 degrees C for the measurement series at the weight ratio of 10:1 to avoid phase separation at high water content. Also, aqueous surfactant solution samples have been investigated as a function of composition and temperature. Water-rich samples consist of micelles that are close to spherical at very low surfactant concentration and grow into anisometric, that is, oblate formed aggregates, at higher surfactant (or surfactant and decanol) concentration. The aggregates grow with increasing temperature, most probably due to dehydration of the hydrophilic groups. In a concentration range around 50 wt % water, the systems form bicontinuous structures. SANS data are used to estimate surfactant film properties using a model developed for interpretation of neutron scattering data from related systems. 相似文献