PREPARATION OF THIN SUPPORT FILM FOR PIXE AND ITS APPLICATION TO TRACE ANALYSIS OF BIOLOGICAL MATERIALS

Abstract

A thin support film is indispensable to make targets of biological material for trace analysis by PIXE. We developed a simple technique for the preparation of high quality support film. Polyvinylformal (PVF) was dissolved in tetrahydrofuran (THF) and the solution was spread on the surface of sucrose solution. The THF was evaporated and a PVF film formed on the surface. The thickness of the PVF film was 0.1µm with good homogeneity. The PVF film was stable to 3MeV proton bombardment and no impurity elements were observed. The continuous X-ray background was <1/20 that of 280µg/cm2 Mylar. We used the PVF film as a support film for some biological materials. Because of the lower X-ray background from the PVF film, K, Ca, Fe, Ni, Cu, Zn, As and Br in 50–100µg of biological materials could be detected.