Energy loss dependent transversal etching rates of heavy ion tracks in plastic

By the method of electrolytical etching track etching rates V_t and corresponding transversal track etching rates V_trans of single heavy ion tracks in thin Makrofol KG foils have been measured at ion energies from 10–480 MeV/u. Makrofol KG foils of 8 μm thickness were irradiated perpendicular to the surface with ⁷⁹Au and ⁵⁴Xe ions at specific energies with energy loss values of REL=(10–90) ^*10³ MeVcm²/g at GSI Darmstadt, Germany, and Lawrence Berkeley Lab., Cal., USA. Using the electrolytical etching method by measuring the resistance of the foil during the etching process (etching conditions: 6n NaOH, room temperature and controlled 50° C) the breakthrough time and track etching rates V_t, V_trans and V_m (bulk etching rate) were analysed. Response curves (V_t/V_m)-1 as a function of Restricted Energy Loss (REL), the maximum extension of the ion induced damage perpendicular to the ion path and the dimension of the ion track core depending on the deposited energy can be estimated.     

Estimation of convergence orders in repeated richardson extrapolation

LetA(h) be an approximation depending on a single parameterh to a fixed quantityA, and assume thatA–A(h)=c ₁ h k ₁ +c ₂ h ^k ₂ +.... Given a sequence ofh-valuesh ₁>h ₂>...>h _n and corresponding computed approximationsA(h _i ), the orders for repeated Richardson extrapolation are estimated, and the repeated extrapolation is performed. Hence in this case the algorithm described here can do the same work as Brezinski'sE-algorithm and at the same time provide a check whether repeated extrapolation is justified.     

The relationship between void size and positron lifetime in neutron irradiated molybdenum

A number of molybdenum specimens, each containing a characteristic void size spectrum, have been subjected to positron lifetime measurements. Although the average void size varied in radius from 9 Å to 45 Å the long positron lifetime in the specimens was remarkably constant with τ₂ = 465±5 ps. Therefore for the range of void sizes examined, this parameter appears to be independent of the void size.     

Radiative lifetimes for excited states in doubly ionized elements (21 ≤ Z ≤ 30) of astrophysical interest

Beam-foil technique has been applied to measurements of radiative lifetimes of 23 terms or levels, all belonging to the 3dⁿ4p (n = 0 to 9) configurations, in Sc(III), Ti(III), V(III), Cr(III), Mn(III), Fe(III), Ni(III) and Zn(III). The experimental lifetimes are in good agreement with lifetimes derived from oscillator-strength calculations, based upon the scaled Thomas-Fermi method, for ultraviolet lines in the spectra of the doubly ionized transition elements.     

Time domain investigation on vibrational dephasing and spectral diffusion in CO-doped solid N2

Infrared picosecond accumulated photon echo experiments have been performed for the first time, using the Orsay Free Electron Laser, on the v = 0-->v = 1 transition of CO in solid nitrogen. The vibrational dephasing time is found to be exceptionally long ( T2>/=120 ns) at low temperature. The analysis of the observed spectral diffusion leads one to assume different energy transfer mechanisms depending on the CO concentration.     

Anchoring of organic molecules to a metal surface: HtBDC on Cu(110)

The interaction of largish molecules with metal surfaces has been studied by combining the imaging and manipulation capabilities of the scanning tunneling microscope (STM). At the atomic scale, the STM results directly reveal that the adsorption of a largish organic molecule can induce a restructuring of a metal surface underneath. This restructuring anchors the molecules on the substrate and is the driving force for a self-assembly process of the molecules into characteristic molecular double rows.     

Continued Fractions and Szegö Polynomials in Frequency Analysis and Related Topics

This paper is an expository survey of recent research on the application of Szegö polynomials and PPC-continuedfractions to the frequency analysis problem described as follows: We want to determine the unknown frequencies ₁, ₂, ..., _I from a sample of N observed values x _N (m), m = 0, 1, ..., N– 1, arising from a continuous waveform that is the superposition of a finite number of sinusoidal waves with frequencies ₁,₂, ..., _I . The method is based on the property that certain zerosof the Szegö polynomials (and poles of the PPC-fraction approximants) converge (as N ) to the frequency points e ⁱ _j , j = ±1, ± 2, ..., ± I. The remaining zeros are bounded away from the unit circle |z|=1, asN . The Levinson algorithm is used to construct the Szegö polynomials and PPC-fractions from the values x _N (m). A discussion is given on connections between the topics: Carathéodory functions,the trigonometric moment problem, Szegö polynomials and PPC-fractions. We also describe applications to Doppler radar, medicine, speech processing, speech therapy, meteorology and ocean tides.