Measurement of proton-induced prompt low energy photons by high resolution spectrometry: The analysis of lanthanides

Photons below 200 keV excited by protons from 1.8 to 5.4 MeV were measured from the lanthanides. The K X-rays were sufficiently resolved for analysis, and the sensitivity attainable was or the order of 100 g.g^–1. Apart from La and Ce, all the rare earths also yielded low energy gamma-rays suitable for qualitative analysis and for the determination of minor components at concentrations above mg.g^–1. Some excitation functions are reported and results are given for test analyses of geological materials.     

Production of charge-induced X-rays during PIXE studies using light and heavy ion-beams

A recently discovered phenomenon of excessively high X-ray production is discussed. The high yield is attributed to the build-up of potential on non-conducting targets irradiated with accelerated ion beams, and the subsequent discharge. Ion-beams of¹H⁺,¹H₂ ⁺,²H⁺,²H₂ ⁺,³He⁺,³He²⁺,⁴He⁺,¹⁴N⁺,¹⁴N²⁺,¹⁶O⁺ and²⁰Ne⁺ were used. A new mechanism of X-ray excitation is proposed. The increased X-ray fluxes produced by this process are suitable for analytical applications of high specificity. The mechanism of excitation associated with the process, factors affecting the high X-ray yields, applications and a general overview of the studies undertaken with the various ion beams are given.     

Applications of prompt particle spectrometry to studies of tinplate surfaces

The use of alpha backscattering is described for the study of oleo-resinous lacquers on tinplate. The lacquer composition is measured as a function of curing temperature, duration of stoving and ageing. The effect of reheating understoved specimens is evaluated and the decomposition during alpha bombardment is measured. The use of prompt proton spectrometry from (d, p) reactions is described for the analysis of stains on tinplate surfaces produced by interaction with protein-rich foods.     

The determination of10B by prompt proton spectrometry

Boron was analysed in ore and glass samples by prompt proton spectrometry, using deuterons of 2.7 MeV to coincide with a region where the excitation function of the¹⁰B(d, p)¹¹B reaction did not vary appreciably with energy. Targets of approximately 300 μg/cm² thick of powdered samples were prepared by centrifugation. Concentrations down to 0.2% were determined. Possible interference by other elements, particularly nitrogen, magnesium and titanium, was investigated.     

PIXE analysis of human stones: Comparison with data from ICP-AES

25 human stone samples previously analyzed by inductively coupled plasma atomic emission spectroscopy /ICP-AES/ and the IAEA Animal Bone Standard Reference Material were used to evaluate trace element analysis by PIXE. Bombardment with 4 MeV protons was used for the determination of Mn, Fe, Cu, Pb, Br, Rb, Sr as well as Ca. PIXE and ICP-AES data gave correlation factors better than 0.97 for the elements Ca, Fe, Zn, Sr and Pb.     

Human hair analysis by PIXE: Pattern recognition of trace element composition

The feasibility is explored of classifying human hair specimens according to their trace metal composition as determined by PIXE. Protons of 3.5 MeV were used to analyse 150 samples by energy-dispersive spectrometry using a Si(Li) detector. The methods of the Minimal Spanning Tree and Non-Linear Mapping were used to establish correlation among the specimens. As a result of distinct groupings obtained by these methods it was inferred that these techniques could usefully be applied to environmental pollution studies.     

The determination of molybdenum and tungsten by high resolution spectrometry of alpha-induced prompt photon emission

A simple, rapid and non-destructive method is described for determining molybdenum and tungsten in steels over the concentration range 0.07 to about 20% by mass. The method uses high resolution spectrometry of the low energy gamma-rays induced by 5 MeV alpha-particle beams. The precision for molybdenum is 2.7% and for tungsten is 0.55% using respectively the 204 and 100.1 keV gamma-rays. Results obtained by Ge(Li) and intrinsic germanium detectors are compared. The extent of interference from other elements is discussed.     

Charge-induced X-ray yields from some metal salts with proton and alpha beams

Previous studies reporting abnormally high X-ray yields from the fluorides of some transition metals were extended to include a variety of other compounds. Using proton beams of 700 and 2000 keV and -beams of 1000 keV the production of abnormally high X-ray yields were critically examined for reproducibility and under different vaccum and bombarding beam conditions.     

The toxic effect of aluminium in vines

The split-root technique was used to study the effect of varying the growth media on the elemental content of nutrient elements in the roots of grape vines. The varieties 2-1 (R99 x Jacquez) and Sauvignon blanc (Vitis vinifera) were grown in Hoagland water culture with and without added aluminium. The elemental concentrations of Mg, Al, Si, P. S, Cl, K and Ca in the dried roots were determined by PIXE. Roots grown in Al-rich media were deficient in Mg and Ca, but enriched in Al. There was a correlation between Al and Si but the uptake differed in the two varieties.     

Trends in metal-biradical exchange interaction for first-row M(II)(nitronyl nitroxide-semiquinone) complexes

We report molecular structures and temperature-dependent magnetic susceptibility data for several new metal complexes of heterospin triplet ground-state biradical ligands. The ligands are comprised of both nitronyl-nitroxide (NN) and semiquinone (SQ) spin carriers. Five compounds are five-coordinate M(II) complexes (M = Mn, Co, Ni, Cu, and Zn), and one is a six-coordinate Ni(II) complex. Five compounds were structurally characterized. During copper complex formation a reaction with methanol occurs to form a unique methoxy-substituted SQ ring. Variable-temperature magnetic susceptibility studies are consistent with strong intraligand (NN-SQ and NN-PhSQ) ferromagnetic exchange coupling. For the five-coordinate Mn, Co, and Ni complexes, the S = 1 ligand is antiferromagnetically coupled to the metal. For both the five-coordinate Cu complex and the six-coordinate Ni complex, the ligand is ferromagnetically coupled to the metal spins in accordance with orbital symmetry arguments. Despite the low molecular symmetries, the predicted trend in metal-ligand exchange interactions is supported by spin dimer analysis based on extended Hückel calculations. For (NN-SQ)NiTp(Cum,Me)() (Tp(Cum,Me)() = hydro-tris(3-cumenyl-5-methylpyrazolyl)borate), an antisymmetric exchange term was required for the best fit of the magnetic susceptibility data. Antisymmetric exchange was less important for the other complexes due to inherently smaller Deltag. Finally, it is shown that intraligand exchange coupling is of paramount importance in stabilizing high-spin states of mixed metal-biradical complexes.