FLUORINE STUDIES WITH A SMALL ACCELERATOR

A small (700 kV) accelerator has been used for studying fluorine in various solids and thin films, via the resonant nuclear reaction (RNR) technique. The strong and relatively narrow resonance in the F-19(p, alpha-gamma)O-16 reaction at 340 keV proton energy turns out to be the most convenient way of determining this element with a high sensitivity at low proton energies. With a typical beam resolution of 1 keV, and a resonance width of 2.4 keV, the depth resolution of fluorine in most materials is in the 0.01 mg/cm2 range. A program for a microcomputer that calculates the excitation curve, given a certain F profile, has been developed and applied to various cases. The proton energy distribution is assumed to be Gaussian; straggling is considered. The F profile may be entered point by point or with any given function. By comparing the calculated and measured F excitation functions, a sensitivity of 10(19) atoms/cm3 is estimated.