Nuclear resonance scattering

Nuclear resonance scattering is an atomistic spectroscopy sensitive to magnetic and electronic properties as well as slow and fast structural dynamics. Applications, which take advantage of both the outstanding properties of third generation synchrotron radiation sources and those of the Mössbauer effect, benefit most. Examples resulting from investigations at the ESRF will be given in applications to high pressure and low temperatures, nano-scale materials, and dynamics of disordered systems. To cite this article: R. Rüffer, C. R. Physique 9 (2008).     

Laser induced charge transfer from Ni to CO adsorbed on (111) and (110) surfaces

Ni(110) and (111) surfaces covered with up to one monolayer of CO were irradiated with the light of a dye laser in the photon energy range 2.0 to 3.4 eV. Two-photon photoemission was observed when the laser light was focussed. Upon defocussing a signal was measured which did not depend on the potential of the sample and showed a linear intensity dependence. It is caused by electrons transferred from the Ni substrate into adsorbate states. The signal vanishes for photon energies below 2 eV. This shows that the adsorbate state lies at most 2 eV above the fermi level. The lifetime τ of the electrons in the adsorbate states is estimated to be 10^?10 < τ < 10^?7 s. No fluorescence in the photon energy range above 1 eV could be detected.     

Energy loss and nucleon exchange in the reaction of 86Kr with 166Er

Projectile-like products from the reaction ⁸⁶Kr on ¹⁶⁶Er at 8.18 MeV/amu have been measured using a large-area position-sensitive ionization chamber. The observed element distributions for a given energy loss are found to be asymmetric. An analysis of the data in terms of the residual kinetic energy above the Coulomb barrier, however, yields symmetric and Gaussian-shaped element distributions. At large energy losses, the centroids of these Gaussian distributions exhibit a drift towards symmetric mass splits. The correlation between the variance of the element distribution σ_z² and the number of exchanged nucleons N_ex is discussed. The exchange mechanism, as described by a simple one-body dissipation model, can account for a large portion of the measured energy loss.     

Eine ringtheoretische Kennzeichnung metabelscher Gruppen

Ohne Zusammenfassung