Generalized filters, the low-pass condition, and connections to multiresolution analyses

We study generalized filters that are associated to multiplicity functions and homomorphisms of the dual of an abelian group. These notions are based on the structure of generalized multiresolution analyses. We investigate when the Ruelle operator corresponding to such a filter is a pure isometry, and then use that characterization to study the problem of when a collection of closed subspaces, which satisfies all the conditions of a GMRA except the trivial intersection condition, must in fact have a trivial intersection. In this context, we obtain a generalization of a theorem of Bownik and Rzeszotnik.     

The scattering of hydrogen,deuterium, and the rare gases from silver (111) single crystals

The scattering of hydrogen, deuterium, and the rare gases from the (111) face of silver has been studied at ultrahigh vacuum. The surfaces were prepared by argon ion bombardment and high temperature annealing. Incident angles between 20° and 65° and surface temperatures between room temperature and 573°K have been investigated. The scattering data exhibit quasi-elastic scattering (He, H₂, D₂), inelastic scattering (Ne, Ar, Kr), and trapping dominated scattering (Xe). Identification of these scattering regimes correlates with D/kT_g and is consistent with similar data from Pt(111) and W(110). The separate effects of microscopic surface roughness and thermal roughening have been identified and thermal attenuation in the elastic regime correlated with dynamical interactions rather than thermal roughening. Trapping and rotational coupling are discussed. Comparison of the data with scattering from epitaxial (111) silver indicates that the epitaxial surfaces are significantly more disordered than the single crystal surfaces.     

Angular-resolved photoemission from NH3 on Ni(110)

NH₃ adsorbed on Ni(110) at a temperature of 100 K has been studied by angular-resolved ultraviolet photoelectron spectroscopy (ARUPS) using synchrotron radiation in the energy range 10 ? ? ω ? 35 eV. From ARUPS it is concluded that NH₃ bonds via its nitrogen lone-pair orbital with its molecular axis normal to the surface. For both the 3a₁ and 1e level dispersion has been found indicating lateral interactions within a compact NH₃ layer. Increasing the NH₃ coverage beyond the chemisorbed monolayer produces a physisorbed monolayer followed by a multilayer deposition of NH₃ phase on top which has been identified by photoemission and thermal desorption. Desorption and partial decomposition result from annealing. At 300 K NH₃ or NH is left at the surface which desorbs almost completely by annealing to 400 K.     

Chemistry of thienopyridines. XXIII. Mass spectra of some N-oxides,sulfoxides, and sulfones

The mass spectral fragmentation patterns of a series of thienopyridine N-oxides, S-oxides, and S,S-dioxides were elaborated as a means of structural determination. Observation of a significant (M-16) peak is diagnostic for the presence of either an N-oxide or an S-oxide function (indistinguishable from one another by this method) but does not occur for an S,S-dioxide function. For a substituted thieno[2,3-b]pyridine 7-oxide, structural rearrangement to a pyridone (followed by emission of carbon monoxide or formyl radical) or side-chain fission may be competitive with de-N-oxygenation. For two tricyclic parent S-oxides, rearrangement and de-S-oxygenation are competing initial processes. For parent S,S-dioxides structural rearrangement precedes fragmentation, wherein the oxygen is ejected in such forms as sulfur monoxide, carbon monoxide, formyl or cyanate radicals, and ketene.