International Journal of PIXE

The ECPSSR theory to calculate the inner-shell ionization cross sections by light-ion impact is studied. Starting from the general formulation of the plane-wave Born approximation, the corrections for the energy-loss effect (E) and the Coulomb-deflection effect (C) of the projectile, and for the binding-polarization effect in the perturbed-stationary-state approach (PSS) and the electronic relativistic effect (R) of the target electron are described. The calculated values in the ECPSSR theory are compared with the experimental data. In general, agreement is good, but there are systematic deviations for low-energy projectiles. The comparison with other theoretical treatments for the inner-shell ionization is discussed.

The principles of photoradiation therapy employing a tumor-seeking agent such as a hematoporphyrin derivative are described. The properties and preparation of hematoporphyrin derivatives and metalloporphyrin synthesis are briefly summarized. We show that PIXE analysis can be used to indicate the degree of a synthesis.

K, L, and M X-rays in the wavelengths between 6Å and 130Å generated by the bombardment of 200 keV protons and other heavy ions were measured by means of a wavelength dispersive Bragg’s spectrometer. The X-ray peak intensity was fairly high in general, while the background was very low. The technique was favorably applied to a practical analysis of several light elements (Be, B, C, N, O, and F). Use of moderate-energy heavy ions considering the wavelength selectivity in X-ray generation was effective for the element analysis. The high-resolution spectrometry in the analytical application of ion-induced X-ray generation was found to be useful for the study of fine electronic structure, e.g. satellite and hypersatellite X-ray study, and of the chemical state of materials.

The resolution of several methods for thin film thickness measurement using PIXE, based on the variation of the proton beam incident energy, is discussed. In order to evaluate the resolution, sputtering of copper films, deposited on aluminum and titanium substrates by argon ions is used. Sputtering yields are obtained through thickness changes, and then compared to other experimental and theoretical values. Good agreement is found, thus confirming the accuracy of PIXE as a method for film thickness determination.

Traces of vanadium, manganese, iron, cobalt, nickel, copper, and zinc were quantitatively extracted with diethyldithiocarbamate (DDTC) in benzene from a digested solution of biological materials and the metal-DDTC complexes were collected into a small amount of polystyrene foam produced by lyophilization of the benzene extract after addition of polystyrene. The polystyrene foam was dissolved in benzene and spread on Mylar film. After drying, a polystyrene film containing metal-DDTC complexes was produced on Mylar film, and then the polystyrene film was peeled from the Mylar film. This film was subjected to PIXE analysis. This method was applied to NBS SRM 1572 citrus leaves and a marine macroalgal sample, and 6 trace metals were simultaneously and accurately determined.

Three tree core samples of Norway spruce (Picea Abies) have been analysed by PIXE. The concentration profiles for 17 elements heavier than sodium have been determined by means of one PIXE measurement every 2 mm along the samples. The samples were collected at Fäxboda, an experimental area north of Uppsala where artificially acidified and limed environmental experiments are made. One sample from each of an acidified, a limed and a reference area has been collected. The main interest is focused on potassium, calcium, manganese, iron, copper and zinc.

All three samples have about the same concentration profile in the heartwood. Large differences are observed in the sapwood. In the sample from the limed area the calcium content is much higher and the iron and chromium. contents are lower than in the sample from the reference area. In the sample from the acidified area the calcium and potassium contents are lower and the manganese, iron and chromium contents are much higher than in the sample from the reference area.

The observed concentration profiles of trace elements in trees indicate that changes in the environment due to acidification can be quantified at an early stage by means of PIXE.