Anisotropic alpha-emission in the223Ra decay chain

Anisotropic α-emission from nuclei in the decay chain from²²³Ra to²⁰⁷Tl has been observed using low temperature nuclear orientation in combination with high resolution α-detection at 4.2 K. Information on partial wave amplitudes as well as hyperfine interactions has been extracted.     

WITCH: A Penning Trap Retardation Spectrometer Combination for Precision Studies of the Weak Interaction

We present data from three seasons of experimental field work designed to recreate ancient Andean coastal ceramic firing techniques. Based on the recent discovery of two different archaeological ceramic production sites in the La Leche river valley of northern coastal Peru, the opportunity arose to apply Mössbauer spectroscopy and other analytical methods to reconstruct ancient firing procedures. Two sets of firings took place in 1993 and 1997 in Batán Grande using a partially restored Formative kiln from about 800 BC, local hardwood and cow dung as fuel. A third experiment followed in 2000 after the discovery of a Middle Sicán ceramics workshop in use between ca. AD 950 and 1050 at Huaca Sialupe, where an exact replica of an ancient kiln was built from local clay, and fired with local wood and cow dung. Additionally, inverted urns found at Huaca Sialupe were tested for their potential use as furnaces for metal working. Mössbauer spectroscopy was used to compare the physical and chemical state of specimens produced in the field experiments with ancient ceramics and with specimens produced in controlled laboratory experiments.     

Metal Ion Complexation: A Route to 2 D Templates?

The two-dimensional ordering of a number of 2,2'-bipyridine derivatives at the liquid/solid interface has been investigated by scanning tunneling microscopy. By appropriate functionalization of the bipyridine units, their intermolecular distance can be tuned, which has proved to be crucial for complexation with metal ions. The in situ addition of metal salts (Pd(2+), Cu(2+)), leading to the formation of metal-bipyridine complexes, has a dramatic influence on the two-dimensional ordering of the molecules and suggests that these complexes could be used as templates.     

On a class of scattering equations

In this paper a class of conservative wave equations treated by Broer and Peletier is considered when a single localised scatterer is present. A criterion for stability in the energy norm is derived. The formal solution of the scattering problem is given. The relation between the location of poles of the scattering matrix, the occurrence of standing wave solutions and the energy criterion is discussed.     

Effects of band mixing on the radiative properties of a quantum well

The effect of band mixing and non-parabolicity on quantum well gain and spontaneous emission is studied using k.p theory. Spectra of gain and spontaneous emission are strongly modified but the relation of maximum gain versus nominal current density is not strongly affected.     

The hyperfine field of sodium in iron

The hyperfine field of NaFe has been measured using Low Temperature Nuclear Orientation of cold implanted²⁴Na. The combination of both the γ-and β-anisotropies yields information on the implantation fraction of Na in Fe. Furthermore, an, upper limit for the relaxation time of Na in Fe could be deduced.